fix(.gitignore): anchor Python build artifacts; recover panel/src/lib (28 files)

The 'lib/' rule (intended for Python virtualenv at repo root) was matching panel/src/lib/, hiding the entire panel API client + utility tree from git. Anchored Python build-artifact rules to the repo root with a leading slash so they only match at the top level. Adds 28 panel/src/lib files that should have been tracked from day one.

panel/src/lib/api/index.ts

@@ -0,0 +1,13 @@
+export { api, API_URL } from "./client";
+export { tasksApi } from "./tasks";
+export { orchestratorApi } from "./orchestrator";
+export { channelsApi } from "./channels";
+export { notificationsApi } from "./notifications";
+export { dashboardApi } from "./dashboard";
+export { knowledgeBaseApi } from "./knowledge-base";
+export { projectsApi } from "./projects";
+export { workSessionsApi } from "./work-sessions";
+export { gitApi } from "./git";
+export { a2aApi } from "./a2a";
+export { streamApi } from "./stream";
+export { groupsApi } from "./groups";