fix(sqlite): include _tenant in shared perms UNIQUE constraint

Match MariaDB's shared shape: under shared tables UNIQUE perms is
(_document, _type, _permission, _tenant). Without _tenant the upsert
path's perm INSERT collides when two tenants legitimately hold the
same role on the same document — exactly what the SharedTables/SQLite
upsert tests trip over once the cursor cascade is gone.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: abnegate

src/Database/Adapter/SQLite.php

@@ -219,12 +219,16 @@ public function createCollection(string $name, array $attributes = [], array $in
             $this->createIndex($id, '_created_at', Database::INDEX_KEY, [ '_createdAt'], [], []);
             $this->createIndex($id, '_updated_at', Database::INDEX_KEY, [ '_updatedAt'], [], []);
 
-            // Permissions UNIQUE stays on (_document, _type, _permission)
-            // for now even under shared tables: composite unique with
-            // _tenant trips upsert flows that re-insert permissions
-            // without first re-loading the existing rows. Revisit once
-            // the upsert permission diff is hardened.
-            $this->createIndex("{$id}_perms", '_index_1', Database::INDEX_UNIQUE, ['_document', '_type', '_permission'], [], []);
+            // Match MariaDB's shared shape: include _tenant in the perms
+            // UNIQUE so two tenants can both grant the same role on the
+            // same document without colliding. Without _tenant the
+            // upsert path for shared tables hits a UNIQUE violation
+            // when a new tenant re-inserts permissions for a row that
+            // already exists in another tenant.
+            $permsColumns = $this->sharedTables
+                ? ['_document', '_type', '_permission', '_tenant']
+                : ['_document', '_type', '_permission'];
+            $this->createIndex("{$id}_perms", '_index_1', Database::INDEX_UNIQUE, $permsColumns, [], []);
             $this->createIndex("{$id}_perms", '_index_2', Database::INDEX_KEY, ['_permission', '_type'], [], []);
 
             if ($this->sharedTables) {