fix(gate): knip sees the watch entry, the build must emit watch.html, and two hand copies are held

- The raw-source contract tests read files from disk (rawSources.testkit)
  instead of import.meta.glob, which knip counted as importing every src file —
  its unused-files lane could never name an orphan. knip now names
  src/watchMain.tsx as an entry (registered in docs/gates.md).
- vite build fails when index.html or watch.html is not emitted.
- The watch-entry import walk follows dynamic import() too.
- audit_metrics.py's plan-code patterns are held equal to the guard's.
- CrashBoundary is domain-free: it moves into components/ui.

frontend/src/lib/navPosition.wiring.contract.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from "vitest";
+import { readSources } from "./rawSources.testkit";
 
 // Every push that opens a new view over the current one remembers the list item it was opened from
 // (`lib/history.rememberNavPosition`), so Back hands focus back to that item. A push that
@@ -10,11 +11,10 @@ import { describe, expect, it } from "vitest";
 // The assertion pins the SET of offending sites and checks the scan found pushes at all: a guard whose
 // glob stops matching is green over nothing.
 
-const files = import.meta.glob(["../**/*.ts", "../**/*.tsx", "!../**/*.test.*"], {
-  query: "?raw",
-  import: "default",
-  eager: true,
-}) as Record<string, string>;
+const files = readSources(__dirname, ["../**/*.ts", "../**/*.tsx", "!../**/*.test.*"]) as Record<
+  string,
+  string
+>;
 
 const EXEMPT: Record<string, string> = {
   "lib/history.ts#_ov": "the overlay stack: an overlay entry opens no view over the page",