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.

tool-images/base.dockerfile

@@ -20,9 +20,10 @@ RUN apt-get update && apt-get install -y \
     sudo \
     && rm -rf /var/lib/apt/lists/*
 
-# Create a non-root user and allow passwordless sudo so the startup
-# permission fixer can adjust ownership of bind-mounted directories.
-RUN useradd -m -s /bin/bash user \
+# Use the shared built-in UID/GID so writable Config Profile mounts can be
+# shared by compatible instances without ownership changes.
+RUN groupadd -g 1000 user \
+    && useradd -m -u 1000 -g 1000 -s /bin/bash user \
     && echo "user ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/user \
     && chmod 0440 /etc/sudoers.d/user
 WORKDIR /home/user