Replace #[allow(dead_code)] on server-only helpers with #[cfg(feature = "server")]
to make the server/WASM split explicit and avoid compiling unused server logic
into the WASM frontend.
- Gate password/session/auth/comment helpers and model parsers with server feature
- Gate related imports and tests accordingly
- Remove genuinely unused CreatePostRequest and CreateCommentRequest
- Keep #[allow(dead_code)] for true dead code (stub methods, unused public APIs)
- Use #[cfg(any(target_arch = "wasm32", test))] for THEME_KEY
- Update AGENTS.md note