fix(gate): close the gaps in the plan-code guard, the button lists and the tooling

- planCodes: the quote and slash lookarounds let the commonest form through (a docstring or test
  title opening with a code, a slash pair); the two real exceptions (an episode titled "E1", ruff's
  E4/E7/E9) are now named and cut first, with cases that fail on the old pattern. audit_metrics
  counts by the same definition.
- button-primitive: both file lists live in the rule body, out of sight of the snapshot and the
  register; each is now pinned to its exact set of ui/ files (red when either is widened).
- check.sh --brief shows a short log whole and keeps the line before each hit, so ruff's rule and
  eslint's file path survive the excerpt.
- lint-changed runs prettier over every changed frontend file, as the gate does, not only code.
- CLAUDE.md and gates.md no longer claim the basedpyright baseline was found harmless: it was never
  triaged, and the reportOptional* entries are the likeliest real bugs.

frontend/src/lib/lintProbe.testkit.ts

@@ -1,3 +1,4 @@
+import { readdirSync } from "node:fs";
 import { fileURLToPath } from "node:url";
 
 import { ESLint } from "eslint";
@@ -35,6 +36,12 @@ export const eslint = new ESLint({
   },
 });
 
+/** Every component file in ui/, by name — for a probe that pins which of them a rule exempts. */
+export const uiFiles = (): string[] =>
+  readdirSync(new URL("../components/ui/", import.meta.url))
+    .filter((f) => f.endsWith(".tsx") && !f.includes(".test."))
+    .sort();
+
 beforeAll(async () => {
   await eslint.lintText("", { filePath: "src/components/__probe.tsx" });
 }, 60_000);