fix(mem0-plugin): use app_id entity scoping, fix tour, add branch tagging

Tour was filtering on metadata.type which missed platform-categorized
memories. Rewritten to use get_memories (list all) + group by platform
categories field. All write hooks now use app_id as top-level entity
param instead of metadata.project_id. Branch stamped on every write.

mem0-plugin/skills/mem0-switch-project/SKILL.md

@@ -40,7 +40,7 @@ The user provides a project name as an argument: `/mem0:switch-project <project-
    (Replace `<PROJECT_NAME>` with the user's chosen project name.)
 
 3. Verify by searching for existing memories:
-   - Call `search_memories` with `query="project"`, `filters={"AND": [{"user_id": "<id>"}, {"metadata": {"project_id": "<PROJECT_NAME>"}}]}`, `limit=1`
+   - Call `search_memories` with `query="project"`, `filters={"AND": [{"user_id": "<id>"}, {"app_id": "<PROJECT_NAME>"}]}`, `limit=1`
 
 4. Print:
    ```