Add ZimaOS install guide, fix stale upstream pin (#124)

[gantoine]

Two unrelated changes, one commit each.

1. ZimaOS install guide

RomM ships in the ZimaOS App Store, so the install is a single click with no compose file or database setup. Adapted from a walkthrough contributed by the ZimaSpace team, reshaped to match the structure of the other install guides.

Added the prerequisites the source material omitted: generating ROMM_AUTH_SECRET_KEY, setting up metadata providers before the first scan, and the folder-naming requirement inside roms/. Screenshots extracted from the contributed PDF.

2. Fixes #124

The root cause isn't a missing hand-written entry. The env var table is generated from upstream env.template at the ref pinned in scripts/sources.toml, and that pin was stale: 5.1.0-beta.2 (2026-07-26) while latest is 5.2.0 (2026-08-20). ENABLE_SCHEDULED_CLEANUP_ORPHANED_RESOURCES landed upstream after the pinned ref, so the generator never saw it.

Bumped the pin and regenerated. The bump also picks up genuine upstream drift, each verified against env.template:

• new REDIS_SAVE_POLICY
• reworded KIOSK_MODE
• SCAN_WORKERS 2 → 1
• WEB_SERVER_CONCURRENCY 3 → 1
• one new platform (Doom) and four metadata-provider icon changes

The same variable was wrong a second time

administration/scheduled-tasks.md listed Cleanup Orphaned Resources as a Manual task with no env var, directly contradicting the fix above. That table comes from a hardcoded list in gen_scheduled_tasks.py marked "as of 4.8.x". Checking it against backend/tasks/ at 5.2.0 showed every scheduled row's env var name was invented — none of these exist upstream:

In the docs	Reality
SWITCH_TITLEDB_FETCH_INTERVAL_CRON	SCHEDULED_UPDATE_SWITCH_TITLEDB_CRON
LAUNCHBOX_SYNC_INTERVAL_CRON	SCHEDULED_UPDATE_LAUNCHBOX_METADATA_CRON
IMAGE_CONVERSION_INTERVAL_CRON	SCHEDULED_CONVERT_IMAGES_TO_WEBP_CRON
RETROACHIEVEMENTS_SYNC_INTERVAL_CRON	SCHEDULED_RETROACHIEVEMENTS_PROGRESS_SYNC_CRON
NETPLAY_CLEANUP_INTERVAL_CRON	no env var, hardcoded always-on
WATCHER_ENABLED	ENABLE_RESCAN_ON_FILESYSTEM_CHANGE

7f6f558 ("Fix SCAN_INTERVAL_CRON env var doesn't exist") was the same class of bug, found one variable at a time.

Rewrote the registry from each task's constructor, added an Enable var column alongside the cron var, and added the four tasks missing entirely (upload tmp cleanup, ZIP cache cleanup, recompute save hashes, sync folder watcher). Also corrected the prose claim that every task has an ENABLE_* var, since three housekeeping tasks are hardcoded always-on.

Follow-up

This will go stale again. sources.toml claims the pin is "bumped automatically by .github/workflows/romm-release-bump.yml", but that workflow does not exist, and gen_scheduled_tasks.py still hardcodes its list instead of fetching upstream. Both are addressed in a stacked PR rather than here, to keep this one reviewable.

Testing

mkdocs build --strict reports no broken links. Generators are idempotent (re-running reproduces the same output). Remaining warnings are pre-existing and unrelated: no libcairo installed locally, and prettier on three *.docker-compose.yml files, both confirmed against a clean stash of main.

🤖 Generated with Claude Code