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/obj-avoid-hybrids.md

@@ -0,0 +1,69 @@
+---
+title: Avoid Hybrid Data-Object Structures
+impact: MEDIUM-HIGH
+impactDescription: prevents worst-of-both-worlds maintenance burden
+tags: obj, hybrid, structure, design
+---
+
+## Avoid Hybrid Data-Object Structures
+
+Hybrids are half object, half data structure. They have functions that do significant things, AND they have public variables or accessors that expose internal structure. Avoid creating these monstrosities.
+
+**Incorrect (hybrid structure):**
+
+```java
+// Half object, half data structure
+public class Employee {
+    // Public data like a data structure
+    public String name;
+    public double salary;
+    public List<String> skills;
+
+    // Behavior like an object
+    public void promote() {
+        this.salary *= 1.1;
+        notifyHR();
+    }
+
+    public void addSkill(String skill) {
+        this.skills.add(skill);
+        updateTrainingRecord();
+    }
+}
+
+// Client code can bypass behavior
+employee.salary = employee.salary * 1.5;  // Skips notifyHR()
+employee.skills.clear();  // Skips updateTrainingRecord()
+```
+
+**Correct (choose one approach):**
+
+```java
+// Pure object - hide data, expose behavior
+public class Employee {
+    private String name;
+    private Money salary;
+    private SkillSet skills;
+
+    public void promote(PromotionDetails details) {
+        this.salary = salary.increase(details.getRaisePercentage());
+        notifyHR(details);
+    }
+
+    public void addSkill(Skill skill) {
+        this.skills.add(skill);
+        updateTrainingRecord(skill);
+    }
+
+    public EmployeeReport getReport() {
+        return new EmployeeReport(name, salary.getAmount(), skills.list());
+    }
+}
+
+// OR pure data structure - no behavior, expose data
+public record EmployeeData(String name, double salary, List<String> skills) {}
+```
+
+Hybrids make it hard to add new functions AND hard to add new data structures.
+
+Reference: [Clean Code, Chapter 6: Objects and Data Structures](https://www.oreilly.com/library/view/clean-code-a/9780136083238/)