feat(edit-history): edit history panel for local claude sessions

Part 1 of #643 (local sessions only; remote follows as its own PR). An
opt-in, per-device header button opens a panel with the active session's
edits, newest first: every Edit/Write/MultiEdit/NotebookEdit of the main
agent and its subagents with its diff, plus images a Bash call rendered or
the agent sent. Remote, Docker and non-claude sessions answer `unsupported`.

- Reads only on request: `?sync=1` when the panel opens; while it is open on
  that session it re-reads after an edit-capable `transcript:tool_end` or a
  `transcript:complete` from the existing transcript watcher. No hook, timer,
  second watcher or new SSE event; a wiring guard pins it.
- Main transcript: the path the transcript watcher follows (hook-reported),
  else `<id>.jsonl` under the session's own CLAUDE_CONFIG_DIR override or
  the server's config dir. A config dir set outside Codeman is found with
  the next hook; until then the panel says so.
- Store: dataPath('edit-history')/<id>.json, 0600 via tmp+rename, capped at
  500 entries and 4 MiB of diff text per session, deleted with the session,
  blocked in isSensitivePath, never fed to /api/search. Every route goes
  through findSessionOrFail with req.
- Images only through existing file surfaces: file-raw inside the
  workspace, the attachment route with notify:false outside it.
- textContent rendering, bounded byte-offset reads, marker-class header
  button, hidden on phones (locked in the mobile policy test).

Docs: Working-With-Files, Settings-Reference, architecture invariants, API
reference, CLAUDE.md key pattern.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

test/mocks/mock-session.ts

@@ -81,6 +81,13 @@ export class MockSession extends EventEmitter {
   claudeSessionIdIsFirstHand: boolean = false;
   /** Mirrors Session.claudeSessionChain — oldest first, current last. */
   claudeSessionChain: string[] = [];
+  /** The per-session CLAUDE_CONFIG_DIR override that Session.claudeConfigDir() reads. */
+  claudeConfigDirOverride: string | undefined = undefined;
+
+  /** Mirrors Session.claudeConfigDir — the override, trimmed; undefined when unset. */
+  claudeConfigDir(): string | undefined {
+    return this.claudeConfigDirOverride?.trim() || undefined;
+  }
 
   /** Mirrors Session.adoptClaudeSessionId, including the first-hand chain rule. */
   adoptClaudeSessionId(newId: string, options: { firstHand?: boolean } = {}): void {