inline terminal emulator, drop xterm.dart dependency

Replace the xterm pub.dev package with owned code under
lib/src/terminal/. Based on xterm.dart v4.0.0 by xuty (MIT).
Quiver LRU replaced with hand-rolled LinkedHashMap cache.
Scrollable removed from TerminalView — scroll events are forwarded
via Listener.onPointerSignal instead. zmodem, debugger, and
suggestion modules stripped as unused.

Also: bundle clide.tmux.conf (no status bar, 50k scrollback,
mouse on, zero escape delay, isolated -L clide socket), bump PTY
read buffer to 64KB, add 2px terminal padding, drop bold
JetBrains Mono registration.

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

pubspec.lock

@@ -410,14 +410,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.0"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      sha256: ea0b925899e64ecdfbf9c7becb60d5b50e706ade44a85b2363be2a22d88117d2
-      url: "https://pub.dev"
-    source: hosted
-    version: "3.2.2"
   shelf:
     dependency: transitive
     description:
@@ -623,14 +615,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.6.1"
-  xterm:
-    dependency: "direct main"
-    description:
-      name: xterm
-      sha256: "168dfedca77cba33fdb6f52e2cd001e9fde216e398e89335c19b524bb22da3a2"
-      url: "https://pub.dev"
-    source: hosted
-    version: "4.0.0"
   yaml:
     dependency: "direct main"
     description:
@@ -639,14 +623,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.3"
-  zmodem:
-    dependency: transitive
-    description:
-      name: zmodem
-      sha256: "3b7e5b29f3a7d8aee472029b05165a68438eff2f3f7766edf13daba1e297adbf"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.0.6"
 sdks:
   dart: ">=3.9.0 <4.0.0"
   flutter: ">=3.32.0"