test: replace product tests that fake the product with real-boundary tests (F)

- design: serve.test.ts drove an inline mirror server; now two tests run the
  real serve() on an ephemeral port (reload confinement, submit exit 0).
- setup-gbrain: rollback + voyage tests execute the template-extracted init
  blocks (3 sites) instead of drifted local bash copies.
- terminal-agent: internalHandler source greps replaced by a behavioral
  /internal/grant + /internal/revoke auth matrix (no/wrong/valid token).
- /health: server-security-surface and the server-auth / security-audit-r2 /
  sidebar-tabs source greps fold into one liveness-only check on the real
  body; the L4 sidecar wiring gets a behavioral /pty-inject-scan test.
- delete tautologies (browser-manager onDisconnect, memory-command #12),
  ios swiftui tap fixture self-check, memory-ingest put_page grep, detach
  source greps, sidebar-agent absence pins, dead-CSS pins + the dead CSS,
  security-audit-r2 Task 1 + the test-only meta-commands re-export,
  duplicate generated-SKILL.md checks.
- make-pdf coverage-gaps cases move into their owner test files.

browse/test/path-validation.test.ts

@@ -1,6 +1,6 @@
 import { beforeAll, describe, it, expect } from 'bun:test';
 import { chromium } from 'playwright';
-import { validateOutputPath } from '../src/meta-commands';
+import { validateOutputPath } from '../src/path-security';
 import { validateReadPath, SENSITIVE_COOKIE_NAME, SENSITIVE_COOKIE_VALUE } from '../src/read-commands';
 import { BLOCKED_METADATA_HOSTS } from '../src/url-validation';
 import { mkdirSync, mkdtempSync, rmSync, symlinkSync, unlinkSync, writeFileSync, realpathSync } from 'fs';