Drop unused small ID Zod statics

[kitlangton]

Summary

• Remove unused derived .zod statics from small ID schemas: PtyID, QuestionID, PermissionID, ProjectID, and EventID.
• Replace the remaining test-only ProjectID.zod.parse(...) usage with ProjectID.make(...).

Testing

• bun typecheck from packages/opencode
• bun test --timeout 5000 test/session/schema-decoding.test.ts
• bunx prettier --check <changed files>
• bunx oxlint <changed files> (existing warnings only, no errors)

Stack

1. Clean up post-Hono references #26903
2. Simplify single-backend HttpApi exerciser #26906
3. Drop unused small ID Zod statics #26908 👈 current