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/security.test.ts

@@ -243,8 +243,9 @@ describe('canary', () => {
 // /health reported a false-green 'protected' indefinitely. The surfaces they
 // covered (SessionState, read/writeSessionState, getStatus, the /health
 // security field, the sidepanel SEC shield) were dead since the PTY terminal
-// rewrite and are now removed. server-security-surface.test.ts pins the
-// removal + the live L4 wiring.
+// rewrite and are now removed. extension-token.test.ts ("GET /health is
+// liveness-only") pins the removal on the real /health body;
+// pty-inject-scan.test.ts pins the live L4 sidecar wiring behaviorally.
 
 // ─── URL domain extraction ───────────────────────────────────