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>

apps/coder/src/services/mcp-server.ts

@@ -25,13 +25,6 @@ interface PendingRow {
   session_id: string;
 }
 
-interface WorktreeRow {
-  id: string;
-  worktree_path: string;
-  agent: string;
-  started_at: string;
-}
-
 interface ProjectPathRow {
   path: string;
 }
@@ -196,28 +189,6 @@ export async function startMcpServer(sql: Sql): Promise<void> {
     },
   );
 
-  // 6. boocoder.list_worktrees
-  server.tool(
-    'boocoder.list_worktrees',
-    'List active worktrees from running tasks',
-    {},
-    async () => {
-      const rows = await sql<WorktreeRow[]>`
-        SELECT id, worktree_path, agent, started_at
-        FROM tasks
-        WHERE worktree_path IS NOT NULL AND state = 'running'
-        ORDER BY started_at DESC
-      `;
-      const items = rows.map((r) => ({
-        task_id: r.id,
-        worktree_path: r.worktree_path,
-        agent: r.agent,
-        started_at: r.started_at,
-      }));
-      return textResult(items);
-    },
-  );
-
   // Connect via stdio
   const transport = new StdioServerTransport();
   await server.connect(transport);