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/cmt-warning-consequences.md

@@ -0,0 +1,66 @@
+---
+title: Use Warning Comments for Consequences
+impact: MEDIUM
+impactDescription: prevents costly mistakes by future maintainers
+tags: cmt, warning, consequences, safety
+---
+
+## Use Warning Comments for Consequences
+
+Comments that warn other programmers about certain consequences are valuable. They prevent others from making mistakes that have non-obvious impacts.
+
+**Incorrect (no warning about hidden dangers):**
+
+```java
+public static SimpleDateFormat makeStandardDateFormat() {
+    return new SimpleDateFormat("yyyy-MM-dd");
+}
+
+public void runExpensiveOperation() {
+    // Process all historical data
+    processAllRecords();
+}
+
+@Test
+public void testWithRealDatabase() {
+    database.connect();
+    // ...
+}
+```
+
+**Correct (warnings prevent mistakes):**
+
+```java
+// WARNING: DateTimeFormatter is thread-safe, but this legacy method returns
+// SimpleDateFormat which is NOT thread-safe. Do not cache or share the result.
+// Consider migrating callers to use DateTimeFormatter.ISO_LOCAL_DATE directly.
+public static SimpleDateFormat makeStandardDateFormat() {
+    return new SimpleDateFormat("yyyy-MM-dd");
+}
+
+// Preferred (Java 8+): thread-safe, no warning needed
+private static final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+
+// WARNING: This operation takes ~30 minutes on production data
+// and consumes significant memory. Run only during maintenance windows.
+public void runExpensiveOperation() {
+    processAllRecords();
+}
+
+// Don't run this test unless you have several hours to kill.
+// Requires real database connection and processes 10M+ records.
+@Ignore("Long-running integration test")
+@Test
+public void testWithRealDatabase() {
+    database.connect();
+    // ...
+}
+```
+
+**Good warnings include:**
+- Thread-safety concerns
+- Performance implications
+- External dependencies or side effects
+- Security considerations
+
+Reference: [Clean Code, Chapter 4: Comments](https://www.oreilly.com/library/view/clean-code-a/9780136083238/)