Silence render-disposed spam, unbreak bundled skills, drop board wake

Three independently ugly bugs that all fed the same log flood:

* Electron's `WebFrameMain.send` writes every "Render frame was disposed"
  to stderr via `console.error`. When the worker fans a second
  agent-event past a reloading renderer, we produced thousands of
  identical lines and stalled the main loop on stderr I/O. Added a
  `mainFrame.detached` guard so the send is short-circuited before
  Electron's own catch block fires, and installed a targeted filter in
  `suppress-warnings.ts` (now actually imported from the entry point)
  so the specific `console.error("Error sending from webFrameMain:"…)`
  noise never reaches the terminal. Any other payload still surfaces.

* `dispatchAgentMessage` accepted the human-reader sentinel as a wake
  target when an agent replied to `__board__` — `wakeAgentIfPossible`
  then called `db.getAgent("__board__")`, threw, and the dispatcher
  kept repeating on every send. Strip `HUMAN_SENDER_ID` at
  `resolveMessageWakeTargets`, and keep a defense-in-depth guard in the
  heartbeat so a stray caller (future automation fan-out) cannot
  reintroduce the crash.

* Pi's skills loader rejects any SKILL.md whose frontmatter `name`
  diverges from its parent directory. The four bundled `my-writing-style`
  copies declared `name: writing-style-skill`, so every install emitted
  a warning and dropped the skill. They also lived as orphan gitlinks
  (mode 160000 without .gitmodules), and the global `*.md` gitignore
  hid every other SKILL.md from version control. Fixed the frontmatter
  to match the dir, converted the dangling submodules to plain trees,
  and allowlisted `builtin-skills/**/*.md` so a fresh clone carries the
  catalogue instead of silently losing it.

builtin-skills/software-engineer/clean-code/references/test-first-principles.md

@@ -0,0 +1,80 @@
+---
+title: Follow FIRST Principles
+impact: MEDIUM
+impactDescription: prevents test suite from becoming 10× slower over time
+tags: test, first, fast, independent, repeatable
+---
+
+## Follow FIRST Principles
+
+Clean tests follow FIRST: Fast, Independent, Repeatable, Self-Validating, and Timely. These properties ensure tests remain useful and maintainable.
+
+**Incorrect (violating FIRST):**
+
+```java
+// Slow - depends on real database
+@Test
+public void testUserQuery() {
+    Connection conn = DriverManager.getConnection(PROD_DB_URL);  // Slow!
+    // ...
+}
+
+// Not Independent - tests depend on each other
+private static User sharedUser;
+
+@Test
+public void test1CreateUser() {
+    sharedUser = userService.create("bob");
+}
+
+@Test
+public void test2UpdateUser() {
+    sharedUser.setName("alice");  // Depends on test1 running first
+}
+
+// Not Repeatable - depends on external state
+@Test
+public void testPayment() {
+    assertTrue(paymentGateway.charge(card, 100));  // Different result each time
+}
+```
+
+**Correct (following FIRST):**
+
+```java
+// Fast - uses mocks, runs in milliseconds
+@Test
+public void queryShouldReturnMatchingUsers() {
+    UserRepository repo = mock(UserRepository.class);
+    when(repo.findByName("bob")).thenReturn(List.of(testUser));
+
+    List<User> result = userService.query("bob");
+
+    assertEquals(1, result.size());
+}
+
+// Independent - each test sets up its own state
+@Test
+public void createShouldReturnNewUser() {
+    User user = userService.create("bob");
+    assertEquals("bob", user.getName());
+}
+
+@Test
+public void updateShouldModifyUserName() {
+    User user = userService.create("bob");
+    user.setName("alice");
+    assertEquals("alice", user.getName());
+}
+
+// Repeatable - uses test doubles
+@Test
+public void chargeShouldReturnTrueOnSuccess() {
+    PaymentGateway gateway = mock(PaymentGateway.class);
+    when(gateway.charge(any(), eq(100))).thenReturn(true);
+
+    assertTrue(paymentService.processPayment(100));
+}
+```
+
+Reference: [Clean Code, Chapter 9: Unit Tests](https://www.oreilly.com/library/view/clean-code-a/9780136083238/)