Fix Docker socket detection when the socket is group-owned, not world-readable (v0.16.22)

ROADMAP.md

@@ -168,3 +168,5 @@ Roughly in priority order:
 `v0.16.20` audits role enforcement across the app after a run of Administration changes and fixes three places where the frontend showed a control the backend would actually reject for Standard Users and Viewers: the Dashboard's "Resync now" button (Needs Attention drift tile) and the Certificates page's "Run certificate check" button are now hidden for anyone who isn't an administrator, since both call administrator-only endpoints. The Access List editor's "Allowed groups" section -- previously always rendered with an empty `state.groups`, so a Standard User just saw a false "No groups have been created yet." -- now shows an accurate note pointing to an administrator instead, both when creating a new Access List and editing an existing one. Also corrected the in-app documentation: the Users & Groups role summary previously said Viewer "can inspect everything," which wasn't true -- Administration (System, Users, Groups, Backups, API Access, Logs & Retention, Danger Zone) is completely invisible to Viewer, the same as Standard, not merely read-only. The role summary, the Access Lists doc's Groups field, the Certificates doc's Check now section, and the Dashboard doc's Resync now section all now say plainly which actions are administrator-only.
 
 `v0.16.21` gives API Access tokens full parity with every other tile type. Tokens now get a real, persistent custom icon -- a new `icon`/`icon_slug` column pair on the `api_tokens` table (added via an idempotent `ALTER TABLE`, safe on existing installs), matching storage functions, and a `tokens` branch in the shared icon-upload/search/URL routes -- plus the same "•••" card menu every other tile has, with Change icon and Revoke token moved into it. While wiring this up, found and fixed a real pre-existing bug: Groups' own "Change icon" menu item has been broken since it shipped, because the frontend code that actually saves an icon never mapped the `groups` kind to anything and silently fell through to the Hosted Sites endpoint, which always 404'd. Also finished the rest of the API Access fix list: the Full access/Read-only counts in the summary bar now only tally active tokens, so they stay consistent with the Active/Revoked split instead of quietly including tokens that can no longer authenticate; a "Hide revoked" toggle sits at the right of that same summary bar for anyone who's revoked enough tokens over time that the tile grid gets cluttered; and the documentation now explains why a revoked token can't be deleted outright -- the record stays for the same accountability reasons the Audit log is never editable.
+
+`v0.16.22` fixes Docker socket detection for the common case where `/var/run/docker.sock` is correctly bind-mounted but Site Gateway still reports "not detected." Root cause: `detectDockerSocket()` checks that the running process can actually read the socket, but the container drops straight from root to the unprivileged `PUID:PGID` with no supplementary groups, and the socket is typically owned `root:docker` on the host with mode 660 -- so a perfectly correct mount still fails an unprivileged read check with no group membership behind it. `docker-entrypoint.sh` now handles this automatically: while still root, it reads the socket's actual group GID directly off the mount (no hardcoded GID -- it varies by host, Unraid, Debian, Synology, and others all differ), creates a matching local group if one doesn't already exist, adds the app user to it, and hands `su-exec` a username instead of a bare `uid:gid` so supplementary groups actually apply via `initgroups()`. Every step is best-effort and guarded: if anything about the detection or group setup fails, the container starts exactly as it always has, just without Docker integration, the same as if the socket weren't mounted at all. Also documented in the System tab's Environment & Integrations section, including the one thing this can't route around: the check runs once at boot, so a container that already has the mount added still needs an actual restart, not just a reload, to pick it up.