ndb: add process_pns for kind-1080 support

## Summary - Update nostrdb submodule to include NIP-PNS (kind-1080) auto-unwrap support - Add `process_pns()` Rust wrapper following the same pattern as `process_giftwraps()` - Regenerate posix bindings with `ndb_process_pns` Depends on: https://github.com/damus-io/nostrdb/pull/122 ## Test plan - [x] `cargo build --features bindgen` succeeds - [x] Bindings correctly include `ndb_process_pns` 🤖 Generated with [Claude Code](https://claude.com/claude-code)