fold project.yaml into pubspec.yaml

pubspec.yaml is now the single source of truth for version and
project metadata. Makefile reads version from pubspec.yaml. All
references to project.yaml across CLAUDE.md, CHANGELOG.md,
decisions, and skills updated.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pubspec.yaml

@@ -1,8 +1,8 @@
 # clide — Flutter desktop IDE for Claude Code.
 #
-# Single package: UI, core subsystems (IPC, PTY, git, pql), and
-# extensions all live here. The Flutter app hosts the IPC server
-# in-process (D-056); tmux owns session persistence (D-041).
+# Single source of truth for project metadata and dependencies.
+# The Flutter app hosts everything in-process (D-056); tmux owns
+# session persistence (D-041).
 #
 # Prefer-zero-deps; every third-party entry is exact-pinned and
 # justified. No carets. See D-031.
@@ -16,6 +16,17 @@ publish_to: none
 version: 2.0.0-dev
 repository: https://git.schweitz.net/jpmschweitzer/clide
 
+# Project metadata (was project.yaml, folded in per D-056).
+# version: above is the single source of truth. The Makefile reads
+# it for build stamping. Cutting a release bumps version + changelog
+# in one commit.
+#
+# maintainers:
+#   Jeroen Schweitzer <jpmschweitzer@gmail.com>
+# license: MIT
+# status: pre-v2.0, interaction model + panel system landed
+# flutter_channel: stable
+
 environment:
   sdk: ">=3.5.0 <4.0.0"
   flutter: ">=3.19.0"