move per-user plugin grants to the user's page

Granting was a checklist of every user on each plugin's page, so "what may
this person use?" meant opening every plugin in turn — and the answer lived
on N pages while the connector half of it already lived on one. Both grant
sections now sit together on #users/{id}: same row list, same disabled chip,
same replace-the-whole-set save. The plugin's own page keeps a read-only
roster of who holds it, linking back to each person.

- db: plugin_access::set_for_user, the per-user twin of set_for_user on
  mcp_catalog_access; set_access stays as the inverse read model
- PluginManager: list_grants_for_user / set_grants_for_user, which omit and
  reject manages_own_access plugins (a box that controls nothing is worse
  than no box)
- GET/PUT /api/users/{id}/plugins, mounted next to /users/{id}/connectors;
  PUT /api/plugins/{id}/access is gone, GET remains as the roster

No push after the write, unlike a connector grant: that one gates a runtime
snapshotted at login, while a plugin grant is re-read from plugin_access on
every request that depends on it (sidebar pages, /plugins/mine, and each
inbound channel message), so a revoke lands with no bus event.

Docs updated with where access is granted, and why mobile-connector is
absent from that list.

crates/skald-core/src/db/mod.rs

@@ -1268,6 +1268,21 @@ mod tests {
         assert!(!plugin_access::has_access(&pool, "telegram", "u1").await.unwrap());
         assert_eq!(plugin_access::users_for_plugin(&pool, "telegram").await.unwrap(), vec!["u2"]);
 
+        // The Users-page write path: one user's grants across every plugin. A
+        // blanket replace, and scoped to that user — u2's telegram grant stands.
+        plugin_access::set_for_user(&pool, "u1", &["comfyui".to_string(), "honcho".to_string()])
+            .await.unwrap();
+        assert_eq!(
+            plugin_access::plugin_ids_for_user(&pool, "u1").await.unwrap(),
+            vec!["comfyui", "honcho"],
+        );
+        assert!(plugin_access::has_access(&pool, "telegram", "u2").await.unwrap());
+        plugin_access::set_for_user(&pool, "u1", &["honcho".to_string()]).await.unwrap();
+        assert_eq!(plugin_access::plugin_ids_for_user(&pool, "u1").await.unwrap(), vec!["honcho"]);
+        plugin_access::set_for_user(&pool, "u1", &[]).await.unwrap();
+        assert!(plugin_access::plugin_ids_for_user(&pool, "u1").await.unwrap().is_empty());
+        assert!(plugin_access::has_access(&pool, "telegram", "u2").await.unwrap());
+
         plugin_user_configs::set(&pool, "telegram", "u2", &serde_json::json!({"linked": true})).await.unwrap();
         assert_eq!(
             plugin_user_configs::get(&pool, "telegram", "u2").await.unwrap(),

crates/skald-core/src/db/plugin_access.rs

@@ -83,8 +83,39 @@ pub async fn revoke(pool: &SqlitePool, plugin_id: &str, user_id: &str) -> Result
     Ok(())
 }
 
-/// Replaces the full access list for a plugin in one shot (the admin UI's
-/// "who can use this" checklist).
+/// Replaces a user's full plugin-grant list in one shot — the Users-page form
+/// ("which plugins may this person use"), the per-user twin of
+/// [`super::mcp_catalog_access::set_for_user`].
+///
+/// A blanket replace is correct because the form is fed the **complete** set of
+/// grantable plugins: every registered plugin except the binding-managed ones
+/// (`Plugin::manages_own_access`), and those never read this table — their
+/// access is their own pairing — so clearing a stale row for one is a no-op.
+///
+/// Nothing has to be pushed after this write: unlike an MCP grant, which gates
+/// a runtime snapshotted at login, a plugin grant is re-read from here on every
+/// request and every inbound channel message, so a revoke takes effect at once.
+pub async fn set_for_user(pool: &SqlitePool, user_id: &str, plugin_ids: &[String]) -> Result<()> {
+    let mut tx = pool.begin().await?;
+    sqlx::query("DELETE FROM plugin_access WHERE user_id = ?")
+        .bind(user_id)
+        .execute(&mut *tx)
+        .await?;
+    for plugin_id in plugin_ids {
+        sqlx::query("INSERT OR IGNORE INTO plugin_access (plugin_id, user_id) VALUES (?, ?)")
+            .bind(plugin_id)
+            .bind(user_id)
+            .execute(&mut *tx)
+            .await?;
+    }
+    tx.commit().await?;
+    Ok(())
+}
+
+/// Replaces the full access list for a plugin in one shot (the plugin-shaped
+/// twin of [`set_for_user`]). No UI writes through this any more — "who may use
+/// what" is edited on the user's page — but it is the honest inverse of the
+/// read model and the cheapest way to set a plugin's audience from a test.
 pub async fn set_access(pool: &SqlitePool, plugin_id: &str, user_ids: &[String]) -> Result<()> {
     let mut tx = pool.begin().await?;
     sqlx::query("DELETE FROM plugin_access WHERE plugin_id = ?")