feat(auth): API key groups with model-level permissions (#2732)

Integrated into release/v3.8.4

src/lib/db/migrations/065_api_key_groups.sql

@@ -0,0 +1,50 @@
+-- Migration 065: API Key Groups & Model Permissions
+-- Enables team/enterprise key grouping with model-level access control.
+
+BEGIN TRANSACTION;
+
+-- Key groups (logical grouping of API keys for team management)
+CREATE TABLE IF NOT EXISTS key_groups (
+  id TEXT PRIMARY KEY NOT NULL,
+  name TEXT NOT NULL,
+  description TEXT NOT NULL DEFAULT '',
+  is_active INTEGER NOT NULL DEFAULT 1,
+  created_at TEXT NOT NULL DEFAULT (datetime('now')),
+  updated_at TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+-- Group-to-model permissions: which models each group can access
+CREATE TABLE IF NOT EXISTS group_model_permissions (
+  id TEXT PRIMARY KEY NOT NULL,
+  group_id TEXT NOT NULL,
+  -- Model identifier (supports wildcards: "gpt-*", "claude-*", "*" for all)
+  model_pattern TEXT NOT NULL,
+  -- Provider constraint (NULL = any provider, otherwise specific provider ID)
+  provider TEXT,
+  -- Allow or deny
+  access_type TEXT NOT NULL DEFAULT 'allow' CHECK(access_type IN ('allow', 'deny')),
+  created_at TEXT NOT NULL DEFAULT (datetime('now')),
+  FOREIGN KEY (group_id) REFERENCES key_groups(id) ON DELETE CASCADE
+);
+
+-- Group-to-key membership
+CREATE TABLE IF NOT EXISTS key_group_members (
+  key_id TEXT NOT NULL,
+  group_id TEXT NOT NULL,
+  created_at TEXT NOT NULL DEFAULT (datetime('now')),
+  PRIMARY KEY (key_id, group_id),
+  FOREIGN KEY (group_id) REFERENCES key_groups(id) ON DELETE CASCADE,
+  FOREIGN KEY (key_id) REFERENCES api_keys(id) ON DELETE CASCADE
+);
+
+-- Indexes
+CREATE INDEX IF NOT EXISTS idx_group_permissions_group
+  ON group_model_permissions(group_id);
+
+CREATE INDEX IF NOT EXISTS idx_group_members_key
+  ON key_group_members(key_id);
+
+CREATE INDEX IF NOT EXISTS idx_group_members_group
+  ON key_group_members(group_id);
+
+COMMIT;