Dashboard Settings page always fails to save (EACCES on /.env inside Docker)

[ViolinKaine]

Summary (Co-Authored by Claude code)

The dashboard's Settings page always fails to save with "Failed to save settings.
Check backend connection." — but it's not actually a backend/API connectivity issue.
The Next.js API route that handles the save writes to a path that only resolves
correctly in local dev (next dev from a git checkout), not in the Docker deployment
that docker-compose.yml documents as the standard way to run the dashboard.

Root Cause

dashboard/app/api/settings/route.ts:5:

const ENV_PATH = path.resolve(process.cwd(), '../.env')

This assumes process.cwd() is the dashboard/ directory inside a full monorepo
checkout, so ../.env resolves to the repo root's .env. That's true for local dev.

But dashboard/Dockerfile sets WORKDIR /app and copies only the built dashboard
output into the image — there's no monorepo layout inside the container, no sibling
.env one directory up, and /.env (where the path resolves to from /app) doesn't
exist and isn't writable by the non-root nextjs user the container runs as.

Result: any Docker-based deployment (i.e. docker-compose.yml as shipped) gets a
write failure on every settings save attempt, surfaced as a generic backend-connection
error that has nothing to do with the actual cause.

Reproducer

1. docker compose --profile ui up (per the repo's own docker-compose.yml)
2. Open the dashboard → Settings
3. Change any field, click "Save to .env"
4. Server-side error (visible via docker compose logs dashboard):

   [Settings API] write error: Error: EACCES: permission denied, open '/.env'
   

5. UI shows: "Failed to save settings. Check backend connection." — misleading, since
   the backend (:8080) was never involved; this route writes directly to a file on
   the dashboard container's own filesystem.

Suggested Fix

The settings route shouldn't write to a file inside the dashboard container's
filesystem at all when running in Docker — that file isn't shared with the backend
container and doesn't persist across image rebuilds either way. Options:

• Have the dashboard call the backend server's own config/settings API (if one
  exists) instead of writing a local .env, so the write actually reaches the process
  that reads it.
• If a shared .env truly needs editing, mount it as a volume into the dashboard
  container at a fixed path and reference that path (not a relative ../) so it
  doesn't depend on cwd.

Happy to open a PR if a preferred direction is confirmed.

Environment

• Deployment: docker compose --profile ui up (repo's own compose file, unmodified
  aside from a local override for uid/gid and Ollama host networking)
• Images built from current main via the repo's Dockerfiles
• Dashboard on :3000, backend on :8080