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.

test/memory-ingest-include-gitignored.test.ts

@@ -14,7 +14,7 @@
  * from a healthy one, and the memory corpus quietly stops growing.
  *
  * Two tests here:
- *  1. Source pin (same shape as memory-ingest-no-put_page.test.ts): the flag
+ *  1. Source pin: the flag
  *     is present in active code, so removing it trips the build.
  *  2. Behavioural proof of the underlying collision, using git's own ignore
  *     machinery. No gbrain and no network required.