feat(api): on-write search reindex after catalogue writes (#17)

Wire best-effort Meilisearch index sync into the admin write paths
(create/update/delete/set_fields/set_visibility). Adds
SearchClient::sync_object (reindex if the object exists, remove if gone —
one uniform path), an optional AppState.search client, and a reindex
helper that logs failures via tracing without failing the committed
write. Server gains MEILI_URL/MEILI_MASTER_KEY/MEILI_INDEX config;
search stays disabled (no-op) when unset. reindex_all remains the
recovery path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/server/Cargo.toml

@@ -22,6 +22,7 @@ api = { path = "../api" }
 auth = { path = "../auth" }
 db = { path = "../db" }
 domain = { path = "../domain" }
+search = { path = "../search" }
 rpassword.workspace = true
 
 [dev-dependencies]