fix(deploy): drop pnpm-workspace.yaml, move config into package.json

Coolify's Nixpacks pulls pnpm 9.15.9, which sees pnpm-workspace.yaml as a
monorepo descriptor and dies with 'packages field missing or empty' the
moment 'pnpm install' starts. The whole reason we kept that file around
was the 'allowBuilds' / 'patchedDependencies' blocks needed by pnpm 11
locally — both have a longstanding equivalent on the 'pnpm' key inside
package.json that pnpm 9 also understands. Consolidated them there and
removed the workspace file entirely.

  package.json
    "pnpm": {
      "onlyBuiltDependencies": ["sharp", "unrs-resolver"],
      "patchedDependencies": {
        "node-fetch-native-with-agent@1.7.2":
          "patches/node-fetch-native-with-agent@1.7.2.patch"
      }
    }

Lockfile regenerated under pnpm 11 locally; install succeeds. The
node-fetch-native-with-agent patch (the Node 26 / undici workaround) is
still applied so Coolify's pnpm install will replicate the fix in the
build container.

package.json

@@ -61,7 +61,10 @@
     "zustand": "^5.0.9"
   },
   "pnpm": {
-    "onlyBuiltDependencies": ["sharp", "unrs-resolver"]
+    "onlyBuiltDependencies": ["sharp", "unrs-resolver"],
+    "patchedDependencies": {
+      "node-fetch-native-with-agent@1.7.2": "patches/node-fetch-native-with-agent@1.7.2.patch"
+    }
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3.3.3",