feat(stats): add launcher stats command and build integration

- Launcher stats subcommand with cleanup mode
- Stats frontend build integrated into Makefile
- CI workflow updated for stats package
- Config example updated with stats section
- mpv plugin menu entry for stats toggle

.github/workflows/ci.yml

@@ -27,13 +27,16 @@ jobs:
           path: |
             ~/.bun/install/cache
             node_modules
+            stats/node_modules
             vendor/subminer-yomitan/node_modules
-          key: ${{ runner.os }}-bun-${{ hashFiles('bun.lock', 'vendor/subminer-yomitan/package-lock.json') }}
+          key: ${{ runner.os }}-bun-${{ hashFiles('bun.lock', 'stats/bun.lock', 'vendor/subminer-yomitan/package-lock.json') }}
           restore-keys: |
             ${{ runner.os }}-bun-
 
       - name: Install dependencies
-        run: bun install --frozen-lockfile
+        run: |
+          bun install --frozen-lockfile
+          cd stats && bun install --frozen-lockfile
 
       - name: Lint changelog fragments
         run: bun run changelog:lint
@@ -49,6 +52,9 @@ jobs:
       - name: Verify generated config examples
         run: bun run verify:config-example
 
+      - name: Internal docs knowledge-base checks
+        run: bun run test:docs:kb
+
       - name: Test suite (source)
         run: bun run test:fast