refactor: codebase audit cleanup — dead code, dedup, module splits

Multi-agent audit + aggressive cleanup across server/web/coder/booterm,
delivered behind a DEFER discipline so none of the in-flight files were
touched. Removes dead code/deps/columns, dedups server + coder helpers,
and splits the oversized modules (tools.ts, opencode-server.ts,
sentinel-summaries, turn.ts, TerminalPane.tsx) behind stable contracts.
Adds 78 parity/unit tests (server 587, coder 323); fixes two latent bugs
(ChatPane queue keys, FileViewerOverlay blank-line parity).

Intended tag: v2.7.12-audit-cleanup.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pnpm-lock.yaml

@@ -26,9 +26,6 @@ importers:
       pg:
         specifier: ^8.13.0
         version: 8.20.0
-      tslib:
-        specifier: ^2.6.3
-        version: 2.8.1
       zod:
         specifier: ^3.23.8
         version: 3.25.76
@@ -207,9 +204,6 @@ importers:
       '@xterm/addon-web-links':
         specifier: 0.11.0
         version: 0.11.0(@xterm/xterm@5.5.0)
-      '@xterm/addon-webgl':
-        specifier: ^0.19.0
-        version: 0.19.0
       '@xterm/xterm':
         specifier: 5.5.0
         version: 5.5.0
@@ -222,9 +216,6 @@ importers:
       lucide-react:
         specifier: ^1.16.0
         version: 1.16.0(react@18.3.1)
-      next-themes:
-        specifier: ^0.4.6
-        version: 0.4.6(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
       radix-ui:
         specifier: ^1.4.3
         version: 1.4.3(@types/react-dom@18.3.7(@types/react@18.3.28))(@types/react@18.3.28)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
@@ -243,9 +234,6 @@ importers:
       remark-gfm:
         specifier: ^4.0.1
         version: 4.0.1
-      shadcn:
-        specifier: ^4.7.0
-        version: 4.7.0(@types/node@20.19.41)(typescript@5.9.3)
       shiki:
         specifier: ^1.29.2
         version: 1.29.2
@@ -277,6 +265,9 @@ importers:
       '@vitejs/plugin-react':
         specifier: ^4.3.1
         version: 4.7.0(vite@5.4.21(@types/node@20.19.41)(lightningcss@1.32.0))
+      shadcn:
+        specifier: ^4.7.0
+        version: 4.7.0(@types/node@20.19.41)(typescript@5.9.3)
       tailwindcss:
         specifier: ^4.3.0
         version: 4.3.0
@@ -2076,9 +2067,6 @@ packages:
     peerDependencies:
       '@xterm/xterm': ^5.0.0
 
-  '@xterm/addon-webgl@0.19.0':
-    resolution: {integrity: sha512-b3fMOsyLVuCeNJWxolACEUED0vm7qC0cy4wRvf3oURSzDTYVQiGPhTnhWZwIHdvC48Y+oLhvYXnY4XDXPoJo6A==}
-
   '@xterm/xterm@5.5.0':
     resolution: {integrity: sha512-hqJHYaQb5OptNunnyAnkHyM8aCjZ1MEIDTQu1iIbbTD/xops91NB5yq1ZK/dC2JDbVWtF23zUtl9JE2NqwT87A==}
 
@@ -3293,12 +3281,6 @@ packages:
     resolution: {integrity: sha512-8Ofs/AUQh8MaEcrlq5xOX0CQ9ypTF5dl78mjlMNfOK08fzpgTHQRQPBxcPlEtIw0yRpws+Zo/3r+5WRby7u3Gg==}
     engines: {node: '>= 0.6'}
 
-  next-themes@0.4.6:
-    resolution: {integrity: sha512-pZvgD5L0IEvX5/9GWyHMf3m8BKiVQwsCMHfoFosXtXBMnaS0ZnIJ9ST4b4NqLVKDEm8QBxoNNGNaBv2JNF6XNA==}
-    peerDependencies:
-      react: ^16.8 || ^17 || ^18 || ^19 || ^19.0.0-rc
-      react-dom: ^16.8 || ^17 || ^18 || ^19 || ^19.0.0-rc
-
   node-addon-api@7.1.1:
     resolution: {integrity: sha512-5m3bsyrjFWE1xf7nz7YXdN4udnVtXK6/Yfgn5qnahL6bCkf2yKt4k3nuTKAtT4r3IG8JNR2ncsIMdZuAzJjHQQ==}
 
@@ -5981,8 +5963,6 @@ snapshots:
     dependencies:
       '@xterm/xterm': 5.5.0
 
-  '@xterm/addon-webgl@0.19.0': {}
-
   '@xterm/xterm@5.5.0': {}
 
   abstract-logging@2.0.1: {}
@@ -7384,11 +7364,6 @@ snapshots:
 
   negotiator@1.0.0: {}
 
-  next-themes@0.4.6(react-dom@18.3.1(react@18.3.1))(react@18.3.1):
-    dependencies:
-      react: 18.3.1
-      react-dom: 18.3.1(react@18.3.1)
-
   node-addon-api@7.1.1: {}
 
   node-domexception@1.0.0: {}