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.

apps/server/src/schema.sql

@@ -1,5 +1,5 @@
 -- v1.13.3: statement_timeout is set at database level via:
---   ALTER DATABASE boocode SET statement_timeout = '30s';
+--   ALTER DATABASE boochat SET statement_timeout = '30s';
 -- ALTER DATABASE can't run inside a DO block, so this is an operational
 -- step rather than schema. Re-apply after a volume reset (the setting
 -- lives in pg_db which survives `docker compose up --build` but NOT a
@@ -30,8 +30,6 @@ CREATE TABLE IF NOT EXISTS messages (
   session_id UUID NOT NULL REFERENCES sessions(id) ON DELETE CASCADE,
   role TEXT NOT NULL,
   content TEXT NOT NULL DEFAULT '',
-  tool_calls JSONB,
-  tool_results JSONB,
   status TEXT NOT NULL DEFAULT 'complete',
   last_seq INT NOT NULL DEFAULT 0,
   created_at TIMESTAMPTZ NOT NULL DEFAULT clock_timestamp()
@@ -39,11 +37,10 @@ CREATE TABLE IF NOT EXISTS messages (
 
 CREATE INDEX IF NOT EXISTS idx_messages_session ON messages(session_id, created_at);
 
--- v1.13.0: granular message parts table for AI SDK migration. Old
--- messages.content / tool_calls / tool_results columns stay authoritative
--- for reads in v1.13.0; this table is dual-written so the swap can happen
--- in a later dispatch without a backfill window. ON DELETE CASCADE means
--- removing a message removes its parts in one go.
+-- v1.13.0: granular message parts table. v1.13.20: legacy tool_calls/
+-- tool_results columns dropped; message_parts is now the sole source of
+-- truth for tool calls, tool results, and reasoning. ON DELETE CASCADE
+-- means removing a message removes its parts in one go.
 CREATE TABLE IF NOT EXISTS message_parts (
   id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
   message_id uuid NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
@@ -142,10 +139,9 @@ ALTER TABLE messages DROP COLUMN IF EXISTS tool_calls;
 ALTER TABLE messages DROP COLUMN IF EXISTS tool_results;
 
 -- v1.13.10: per-tool token cost rolling window. Derives from
--- messages_with_parts (the v1.13.1-B view that COALESCEs message_parts over
--- the legacy JSON column) so this works whether the chat predates v1.13.0
--- or postdates v1.13.2 (column drop). No new write site — all source data
--- already lands via the existing tool-phase.ts:94-95 UPDATE.
+-- messages_with_parts (the v1.13.1-B view; v1.13.20 removed the legacy
+-- JSON-column COALESCE fallback — parts are sole source). No new write
+-- site — all source data already lands via tool-phase.ts:94-95 UPDATE.
 --
 -- Attribution model: equal split. A turn emitting N tool calls divides its
 -- prompt/completion tokens by N before attribution. See v1.13.10 dispatch
@@ -352,7 +348,7 @@ INSERT INTO settings (key, value) VALUES ('theme_mode', '"dark"') ON CONFLICT (k
 ALTER TABLE projects ADD COLUMN IF NOT EXISTS default_system_prompt TEXT NOT NULL DEFAULT '';
 ALTER TABLE projects ADD COLUMN IF NOT EXISTS default_web_search_enabled BOOLEAN NOT NULL DEFAULT false;
 ALTER TABLE sessions ADD COLUMN IF NOT EXISTS web_search_enabled BOOLEAN;
-ALTER TABLE sessions ADD COLUMN IF NOT EXISTS tags TEXT[] DEFAULT '{}';
+ALTER TABLE sessions DROP COLUMN IF EXISTS tags;
 
 -- v1.11: anchored rolling compaction.
 --   compacted_at  — marks rows that are "behind the curtain" of the latest
@@ -391,9 +387,7 @@ CREATE TABLE IF NOT EXISTS tasks (
   model             TEXT,
   mode_id           TEXT,
   thinking_option_id TEXT,
-  feature_values    JSONB,
   execution_path    TEXT CHECK (execution_path IS NULL OR execution_path IN ('native','acp','pty','qwen')),
-  worktree_path     TEXT,
   cost_tokens       INTEGER,
   started_at        TIMESTAMPTZ,
   ended_at          TIMESTAMPTZ,