build: update pnpm to v11 and pin exact dependencies (#441)

- bump `packageManager` to `[email protected]`, move settings to `pnpm-workspace.yaml`, drop the npm-only `.npmrc`
- pin all dependencies to exact versions

Reviewed-on: https://gitea.com/gitea/docs/pulls/441
Reviewed-by: Lunny Xiao <[email protected]>
Co-authored-by: silverwind <[email protected]>
Co-committed-by: silverwind <[email protected]>

pnpm-workspace.yaml

@@ -0,0 +1,8 @@
+savePrefix: ''
+dedupePeerDependents: false
+updateNotifier: false
+minimumReleaseAge: 0
+
+allowBuilds:
+  '@swc/core': true
+  core-js: false