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/src/config.rs

@@ -27,4 +27,19 @@ pub struct Config {
         default_value_t = true
     )]
     pub cookie_secure: bool,
+
+    /// Meilisearch base URL (e.g. `http://localhost:7700`). On-write search indexing
+    /// is enabled only when both this and `--meili-master-key` are set; otherwise
+    /// search is disabled (best-effort feature) and `reindex_all` remains the rebuild
+    /// path.
+    #[arg(long = "meili-url", env = "MEILI_URL")]
+    pub meili_url: Option<String>,
+
+    /// Meilisearch API key (master or a scoped key).
+    #[arg(long = "meili-master-key", env = "MEILI_MASTER_KEY")]
+    pub meili_master_key: Option<String>,
+
+    /// Meilisearch index name for catalogue objects.
+    #[arg(long = "meili-index", env = "MEILI_INDEX", default_value = "objects")]
+    pub meili_index: String,
 }