bundle JetBrains Mono for terminal panes

Vendor the 4 core weights (Regular, Italic, Bold, BoldItalic) of
JetBrains Mono v2.304 under app/assets/fonts/jetbrains_mono/, ~1 MB
total. OFL license checked in alongside. Declared as the
JetBrainsMono family in pubspec so Flutter bundles it automatically.

app/lib/widgets/src/typography.dart exposes clideMonoFamily plus a
platform-ordered fallback chain (SF Mono / Menlo / Monaco →
JetBrains Mono system install / Fira Code / Hack / DejaVu / Liberation →
Cascadia / Consolas → monospace) for web builds and test harnesses
that don't load asset fonts. Terminal widgets pick both up via a
single import.

Co-Authored-By: Claude <noreply@anthropic.com>

CHANGELOG.md

@@ -18,6 +18,16 @@ heading, and (b) bumping `project.yaml` `version:` in the same commit.
 
 ### Added
 
+- JetBrains Mono bundled as `app/assets/fonts/jetbrains_mono/` —
+  Regular / Italic / Bold / BoldItalic weights (OFL-licensed,
+  license file checked in alongside). Declared as the `JetBrainsMono`
+  family in `app/pubspec.yaml`. `app/lib/widgets/src/typography.dart`
+  exposes `clideMonoFamily` + `clideMonoFamilyFallback` for terminal
+  panes and any other monospace surface; fallback chain covers
+  macOS / Linux / Windows for the web build path and for harnesses
+  that don't load asset fonts. Additional weights
+  (Thin/Light/Medium/ExtraBold) can be added on demand.
+
 - `ptyc/` — the C PTY-spawn helper, peer of `pql` per
   [`D-005`](decisions/architecture.md#d-005-dart-core-sidecar-dissolved-ptyc-as-pql-peer).
   One-shot, libc-only, ~400 LOC. Reads a JSON request on stdin

app/assets/fonts/jetbrains_mono/OFL.txt

@@ -0,0 +1,93 @@
+Copyright 2020 The JetBrains Mono Project Authors (https://github.com/JetBrains/JetBrainsMono)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://scripts.sil.org/OFL
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

app/lib/widgets/src/typography.dart

@@ -0,0 +1,32 @@
+/// Typography constants shared across widgets.
+///
+/// Terminal panes, diff views, and any other monospace surface should
+/// import from here rather than hardcoding a family. The fallback chain
+/// exists for web builds + platforms where the bundled `JetBrainsMono`
+/// asset isn't picked up (rare, but possible during `flutter test` if
+/// assets aren't declared in the harness).
+library;
+
+/// The bundled monospace family. Always resolved first.
+const String clideMonoFamily = 'JetBrainsMono';
+
+/// System fallback chain. Ordered by platform prevalence + quality of
+/// programming-ligature / box-drawing coverage.
+const List<String> clideMonoFamilyFallback = [
+  // macOS
+  'SF Mono',
+  'Menlo',
+  'Monaco',
+  // Linux
+  'JetBrains Mono',  // if the user has it system-installed under the
+                     // canonical PostScript name
+  'Fira Code',
+  'Hack',
+  'DejaVu Sans Mono',
+  'Liberation Mono',
+  // Windows
+  'Cascadia Code',
+  'Consolas',
+  // Last resort
+  'monospace',
+];

app/lib/widgets/widgets.dart

@@ -13,6 +13,7 @@ export 'src/clide_surface.dart';
 export 'src/clide_tab_bar.dart';
 export 'src/clide_text.dart';
 export 'src/clide_tooltip.dart';
+export 'src/typography.dart';
 export 'src/icons/check.dart';
 export 'src/icons/chevron.dart';
 export 'src/icons/dot.dart';

app/pubspec.yaml

@@ -53,3 +53,19 @@ flutter:
   assets:
     - lib/kernel/src/theme/themes/
     - lib/kernel/src/i18n/catalog/
+
+  # JetBrains Mono — bundled so terminal panes render consistently
+  # regardless of what the user has system-installed. OFL-licensed;
+  # see assets/fonts/jetbrains_mono/OFL.txt. Thin/Light/Medium/
+  # ExtraBold weights can be added later if a theme needs them.
+  fonts:
+    - family: JetBrainsMono
+      fonts:
+        - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Regular.ttf
+        - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Italic.ttf
+          style: italic
+        - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Bold.ttf
+          weight: 700
+        - asset: assets/fonts/jetbrains_mono/JetBrainsMono-BoldItalic.ttf
+          weight: 700
+          style: italic