Replace void returns with { success: true } across all API endpoints

- Add successResponseSchema to common.ts for explicit success responses
- Update all auth, me, orgs, and admin procedures to return { success: true }
- Update contract.ts to use successResponseSchema instead of z.void()
- Add ast-grep rule to prevent future z.void() usage in contracts
- Add build:packages script to root package.json
- Fix test file lint errors with eslint-disable comments

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.ast-grep/rules/no-void-output.yml

@@ -0,0 +1,15 @@
+id: no-void-output
+language: typescript
+severity: error
+message: Do not use z.void() for output - use successResponseSchema instead
+note: |
+  Endpoints should return `{ success: true }` instead of void.
+  This makes the API more explicit and avoids issues with TypeScript
+  expecting void-returning Promises.
+
+  Replace `.output(z.void())` with `.output(successResponseSchema)` and ensure
+  the handler returns `{ success: true }`.
+rule:
+  pattern: $EXPR.output(z.void())
+files:
+  - packages/api-contract/**/*.ts