Replace the placeholder-art screenshots with renders of a real library, so the
store listing shows real album and artist art and names.
The generator (DemoScreenshotTest, run with `gradle :app:demoScreenshots`) syncs
the public Navidrome demo (demo.navidrome.org) into an in-memory database using
the normal SyncService pipeline, derives the theme colours from the fetched
cover art, and renders each screen. The synced data and cover art stay in memory
and are never written to the repository; only the resulting PNGs are committed.
The test is excluded from the unit-test tasks and is not part of CI.
Also reverts the screenshot fixture palette tweak from the previous commit,
which the real art makes unnecessary.
Trim the explanatory comments to short quirk notes, drop the module headers, and fail cleanly: navidrome/gonic now kill their process if they never become ready and the entrypoint always tears down. The prune test waits for the removal to appear in the album list rather than for the scan flag. Correct the AGENTS token-auth note (lms answers 42, Nextcloud 41) and give CI more headroom.
Run the integration harness from its own devshell so the server packages stay out of the everyday shell. Add lms and a Nextcloud Music instance to the harness and extend the suite with auth-fallback, media, error, write round-trip, multi-source and prune tests.
The auth test caught that lms answers OpenSubsonic error 42 (not 41) when it refuses token auth, so the client now falls back on both codes.
Spell out the sync contract: browsing, filtering and sorting never touch the network,
only media bytes and images are on-demand, and a server-derived sort key has to land in a
local column at sync time rather than being requested lazily.
adds docs/architecture.md (stack, layers, data model, sync, search, networking, testing, CI), docs/implementation-plan.md (phases and status), and AGENTS.md for agents and contributors
austinried