fix(sqlitestore): add tenant_id filter to GetSkillHashBySlug and GetNextVersion

SQLite implementations were missing tenant_id WHERE clauses that the
PostgreSQL equivalents have. While Lite edition is single-tenant in
practice, this maintains dual-DB parity and prevents potential issues
if the codebase evolves.

Follows the same pattern as other methods in the file (GetSkillFilePath,
CreateSkillManaged, etc.) that use store.TenantIDFromContext with
MasterTenantID fallback.

internal/store/sqlitestore/skills_crud.go

@@ -188,23 +188,31 @@ func (s *SQLiteSkillStore) GetSkillFilePath(ctx context.Context, id uuid.UUID) (
 }
 
 // GetSkillHashBySlug returns the file_hash and version of the latest non-deleted skill
-// version for the given slug.
+// version for the given slug, scoped to the current tenant.
 // Returns ok=false when no matching row exists.
 func (s *SQLiteSkillStore) GetSkillHashBySlug(ctx context.Context, slug string) (string, int, bool) {
+	tid := store.TenantIDFromContext(ctx)
+	if tid == uuid.Nil {
+		tid = store.MasterTenantID
+	}
 	var hash string
 	var version int
 	err := s.db.QueryRowContext(ctx,
 		`SELECT COALESCE(file_hash, ''), version FROM skills
-		 WHERE slug = ? AND status != 'deleted'
+		 WHERE slug = ? AND tenant_id = ? AND status != 'deleted'
 		 ORDER BY version DESC LIMIT 1`,
-		slug,
+		slug, tid,
 	).Scan(&hash, &version)
 	return hash, version, err == nil
 }
 
 func (s *SQLiteSkillStore) GetNextVersion(ctx context.Context, slug string) int {
+	tid := store.TenantIDFromContext(ctx)
+	if tid == uuid.Nil {
+		tid = store.MasterTenantID
+	}
 	var maxVersion int
-	s.db.QueryRowContext(ctx, "SELECT COALESCE(MAX(version), 0) FROM skills WHERE slug = ?", slug).Scan(&maxVersion)
+	s.db.QueryRowContext(ctx, "SELECT COALESCE(MAX(version), 0) FROM skills WHERE slug = ? AND tenant_id = ?", slug, tid).Scan(&maxVersion)
 	return maxVersion + 1
 }