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/gen-skill-docs.test.ts

@@ -196,17 +196,6 @@ describe('gen-skill-docs', () => {
     expect(commands).toEqual(sorted);
   });
 
-  test('generated header is present in SKILL.md', () => {
-    const content = fs.readFileSync(path.join(ROOT, 'SKILL.md'), 'utf-8');
-    expect(content).toContain('AUTO-GENERATED from SKILL.md.tmpl');
-    expect(content).toContain('Regenerate: bun run gen:skill-docs');
-  });
-
-  test('generated header is present in browse/SKILL.md', () => {
-    const content = fs.readFileSync(path.join(ROOT, 'browse', 'SKILL.md'), 'utf-8');
-    expect(content).toContain('AUTO-GENERATED from SKILL.md.tmpl');
-  });
-
   test('snapshot flags section contains all flags', () => {
     const content = readSkillUnion('browse');
     for (const flag of SNAPSHOT_FLAGS) {
@@ -329,7 +318,7 @@ describe('gen-skill-docs', () => {
   test('no generated SKILL.md contains unresolved placeholders', () => {
     for (const skill of CLAUDE_GENERATED_SKILLS) {
       const content = fs.readFileSync(path.join(ROOT, skill.dir, 'SKILL.md'), 'utf-8');
-      const unresolved = content.match(/\{\{[A-Z_]+\}\}/g);
+      const unresolved = content.match(/\{\{\w+\}\}/g);
       expect(unresolved).toBeNull();
     }
   });