fix(hooks,test): harden background rewake, fix hook timeout units, stabilize CI teardown

Follow-ups from the PR #175/#176 reviews:

- Rewake helper self-terminates on its own 6h deadline and when orphaned,
  instead of relying on Claude Code to reap the poller
- Rewake marker versioned (V2) with a version-agnostic ownership prefix, so
  future script updates replace older handlers instead of duplicating them;
  regression test covers the V1 to V2 swap
- HOOK_TIMEOUT_MS renamed to HOOK_TIMEOUT_SECONDS = 10: the hook timeout
  field is seconds (the CLI multiplies by 1000), so the curl hooks have
  effectively had a ~2.8h timeout since COD-54
- Test echo PTY switches to raw mode: each input byte echoes exactly once
  (tty line discipline doubled every line and buffered until Enter)
- test/setup.ts: drain in-flight console-log rpc forwards before environment
  teardown (fixes the EnvironmentTeardownError that failed CI twice on the
  merge commit with all 3820 tests passing), clean the temp home on process
  exit (fully-skipped files leaked it), fix the Windows Playwright cache
  fallback path
- test/webview-proxy.test.ts: stop naming the vitest environment directive in
  prose; vitest matches it inside comments and silently ran the whole file
  under the jsdom environment while the comment claimed node
- CLAUDE.md: document the temp-HOME and echo-PTY test isolation

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/session.ts

@@ -181,7 +181,12 @@ const DEFAULT_PTY_COLS = 120;
 const DEFAULT_PTY_ROWS = 40;
 const TMUX_DISPLAY_TIMEOUT_MS = 2000;
 const IS_TEST_MODE = !!process.env.VITEST;
-const TEST_PTY_SCRIPT = 'process.stdin.pipe(process.stdout);';
+/**
+ * Echo transport for the test-mode PTY attach. Raw mode disables the tty line
+ * discipline, so each input byte flows back exactly once and immediately; without
+ * it, tty echo doubles every line and canonical buffering holds bytes until Enter.
+ */
+const TEST_PTY_SCRIPT = 'if (process.stdin.isTTY) process.stdin.setRawMode(true); process.stdin.pipe(process.stdout);';
 /** Delay before the in-container Claude CLI version probe (lets the container start). */
 const DOCKER_CLI_VERSION_PROBE_DELAY_MS = 3000;