base_vs_extension_boundary

Clear ownership so install steps do not write to the wrong store:
- Extension package / activate / welcome webview → extension_installation ( extension host + `globalState` onboarding key ).
- Activity bar, LSP, chat participant, Ideas Summary → extension runtime after activation_sequence.
- `.reqlan/` marker, `config.json`, `.rqignore`, ideas index, index diagnostics sqlite → base_installation under `<base>/.reqlan/`.
- Cursor `rq-*` skills + MCP json → workspace_agent_files under `<workspace>/.cursor/`.
Do not store agent skills or MCP config inside `.reqlan`. Do not treat welcome-webview globalState as base-local memory.

Interactive page: base_vs_extension_boundary