feat: accept kind:1 text notes and kind:3 follow lists (NIP-01/NIP-02)

[tlongwell-block]

Summary

Open Sprout to standard Nostr social events — kind:1 (text notes) and kind:3 (follow/contact lists). These are the two most fundamental Nostr event types; without them, standard clients like Damus and Amethyst pointed at Sprout cannot post or read basic notes.

kind:1 gives Sprout a global "company Twitter" feed. kind:3 gives clients the follow graph to filter it. Together they let Sprout act as a superset of a standard Nostr relay: a decent relay that also has enterprise team collaboration features.

Also fixes three bugs in replace_addressable_event() that affected existing kind:0 profile replacement.

Changes

File	What
sprout-core/kind.rs	Add KIND_TEXT_NOTE = 1, is_replaceable() helper, update ALL_KINDS
sprout-relay/handlers/ingest.rs	Allow kind:1 (MessagesWrite) and kind:3 (UsersWrite); route all replaceables through replace_addressable_event(); force channel_id = None for global-only kinds; generalize channel-scoped token guard
sprout-db/lib.rs	Rewrite replace_addressable_event() — atomic tx, pg_advisory_xact_lock, stale-write protection with same-second id tie-break, IS NOT DISTINCT FROM for NULL safety, checked INSERT with rollback
sprout-relay/handlers/req.rs	NIP-50 search includes global events via __global__ sentinel
sprout-relay/api/search.rs	/api/search includes global events; nullable channel_name
sprout-relay/handlers/side_effects.rs	Honor was_inserted before dispatching discovery events
sprout-search/index.rs	__global__ sentinel for Typesense (see below)
sprout-search/query.rs	Map __global__ back to None in search hits
sprout-auth/scope.rs	Update UsersWrite comment for kind:3
sprout-relay/nip11.rs	Add NIP-2 to supported_nips
desktop/src-tauri/models.rs	SearchHitInfo channel fields → Option<String>
desktop/src/*.ts{,x}	Nullable channel_id/channel_name across types + UI null-guards

Bugs fixed in replace_addressable_event()

These affected existing kind:0 profile replacement:

1. Non-atomic delete+insert — DELETE committed, then insert_event() called outside the tx. Crash between = data loss. → Single transaction.
2. No stale-write protection — Older event could overwrite newer. → created_at comparison + same-second id tie-break (lowest wins, per NIP-16).
3. NULL comparison bug — channel_id = $3 is false when NULL. Global events silently failed to replace. → IS NOT DISTINCT FROM.
4. No concurrency protection — Two concurrent first-inserts could both succeed. → pg_advisory_xact_lock with FNV-1a hash key.

Typesense discovery

During live testing, Typesense 27.1's channel_id:__missing__ filter returned 0 results even for documents where the field was truly absent. Tested absent, null, and omitted — all return 0. Appears to be a Typesense bug or undocumented limitation.

Fix: Use __global__ sentinel value instead. Collision-proof (channel_id is UUID-shaped everywhere else), mapped back to None in search hits. Requires just reindex-search after deploy to backfill historical docs. Not a regression — pre-existing global events (kind:0 only) were already excluded from search by the old .filter(|h| h.channel_id.is_some()).

Testing

• 302 unit tests pass (40 core + 53 auth + 50 db + 148 relay + 11 search), 0 failed
• 9 live acceptance tests pass against a running local relay:
  • kind:1 accepted, queryable via REQ, searchable via /api/search
  • kind:3 accepted, replacement works, stale-write rejected
  • kind:0 replacement still works (regression)
  • NIP-11 shows NIP-2
  • Combined search returns channel + global events together
• cargo clippy clean, cargo fmt clean, biome check clean

Deploy notes

• Run just reindex-search after deploy to backfill the __global__ sentinel for historical global events in Typesense.

Out of scope

• Desktop UI for notes feed / follow management (separate frontend PR)
• MCP tools for notes/follows (separate PR)
• NIP-33 parameterized replaceable events (PR 2)
• NIP-16 in supported_nips (deferred until more replaceable kinds are accepted)