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/normalize-agent-status.ts

@@ -21,72 +21,3 @@
  */
 
 export type AgentStatus = 'working' | 'blocked' | 'idle' | 'error';
-
-/** The coarse signal a raw vendor event collapses to. */
-export type AgentEventBucket = 'working' | 'blocked' | 'done';
-
-// Each bucket lists the canonical vendor event names. Lookup is
-// case-insensitive AND separator-insensitive (snake_case / camelCase /
-// PascalCase all fold to the same key), so we normalize the raw input the same
-// way before matching rather than enumerating every spelling here.
-const WORKING_EVENTS = [
-  'SessionStart',
-  'UserPromptSubmit',
-  'UserPromptSubmitted',
-  'PostToolUse',
-  'PostToolUseFailure',
-  'BeforeAgent',
-  'AfterTool',
-  'task_started',
-] as const;
-
-const BLOCKED_EVENTS = [
-  'PreToolUse',
-  'Notification',
-  'PermissionRequest',
-  'exec_approval_request',
-  'apply_patch_approval_request',
-  'request_user_input',
-] as const;
-
-const DONE_EVENTS = [
-  'Stop',
-  'AfterAgent',
-  'SessionEnd',
-  'task_complete',
-  'agent-turn-complete',
-] as const;
-
-/**
- * Fold a raw event name to a separator/case-insensitive key:
- * strip every non-alphanumeric character and lowercase. So `post_tool_use`,
- * `postToolUse`, `PostToolUse`, and `POST-TOOL-USE` all map to `posttooluse`.
- */
-function foldKey(raw: string): string {
-  return raw.replace(/[^a-z0-9]/gi, '').toLowerCase();
-}
-
-function buildLookup(
-  groups: ReadonlyArray<readonly [AgentEventBucket, readonly string[]]>,
-): Map<string, AgentEventBucket> {
-  const map = new Map<string, AgentEventBucket>();
-  for (const [bucket, names] of groups) {
-    for (const name of names) map.set(foldKey(name), bucket);
-  }
-  return map;
-}
-
-const EVENT_LOOKUP = buildLookup([
-  ['working', WORKING_EVENTS],
-  ['blocked', BLOCKED_EVENTS],
-  ['done', DONE_EVENTS],
-]);
-
-/**
- * Map a raw vendor hook-event name to its normalized bucket, or `null` when the
- * name is unknown / undefined. Case- and separator-insensitive.
- */
-export function normalizeAgentEvent(raw: string | undefined): AgentEventBucket | null {
-  if (!raw) return null;
-  return EVENT_LOOKUP.get(foldKey(raw)) ?? null;
-}