fix(ci): exclude project-local pnpm store from lint/format scans

CI runners configure pnpm with --store-dir=.pnpm-store (project-local
CAS) for cross-run caching. Prettier and ESLint were scanning into it
and finding 333 unformatted JSON files.

Added to .prettierignore and eslint.config.js globalIgnores:
- .pnpm-store / .pnpm — pnpm content-addressable store variants
- coverage — future test runs (Vitest in Phase 3)
- .cache — generic build cache directory

Local Windows trees aren't affected (pnpm uses the global store at
~/.local/share/pnpm/store) but the rules cover both paths.

eslint.config.js

@@ -7,7 +7,14 @@ import prettierRecommended from 'eslint-plugin-prettier/recommended';
 import { defineConfig, globalIgnores } from 'eslint/config';
 
 export default defineConfig([
-  globalIgnores(['dist', 'src/routeTree.gen.ts']),
+  globalIgnores([
+    'dist',
+    'src/routeTree.gen.ts',
+    // CI runners may use a project-local pnpm CAS at .pnpm-store.
+    '.pnpm-store',
+    '.pnpm',
+    'coverage',
+  ]),
   {
     files: ['**/*.{ts,tsx}'],
     extends: [