feat: add live config profile refresh

- Standardize built-in tool users for shared writable profile mounts
- Mount canonical non-Git profile sources across compatible instances
- Report restart-required outcomes and guard active profile deletion
- Surface restart feedback in config profile editing

Quality gates: frontend build passed; backend py_compile and LSP passed.
Skipped: backend pytest/Ruff unavailable; Docker/manual checks not approved.

openspec/changes/live-config-profile-refresh/design.md

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+# Design: Live Config Profile Refresh
+
+## Canonical working copies
+
+Each non-Git Config Profile owns canonical host-side storage. Directory mounts use canonical profile directories; each top-level profile file uses a canonical host file bind-mounted under the container working directory. All compatible instances selected for the profile mount the same sources, so UI and container edits are immediately shared.
+
+## Container compatibility
+
+Supported built-in tools standardize on one non-root user/group. Existing instances retain their current image/user and report `restart_required`. Custom tools are not rewritten; tools that do not opt into the shared user/group return `incompatible_permissions`.
+
+## Save behavior
+
+A profile save writes canonical profile files atomically per file. The save response reports affected compatible instances, `restart_required` topology/runtime changes, `incompatible_permissions`, and detectable overwrite warnings. Last writer wins; no merge or lock protocol is imposed.
+
+## Scope boundaries
+
+Git mount mutation is explicitly deferred. Workspace/repository mounts are never changed. Profile deletion is rejected while running instances still use the profile.