Remove central release/ repo: apps push icons + metadata on promote

[cyberb]

Problem

App icons and metadata (name, description, summary, ui, required) live in a centralized release/ repo:

• release/index-v2 — JSON catalog of every app
• release/images/<app>-128.png — icons

Adding or updating an app requires a manual commit to release/. Apps cannot ship metadata changes alongside their own code — they're decoupled from their own description and icon.

Proposal

Each app pushes its own icon and metadata during its existing promote step. Drop the central release/ catalog.

Who reads release/ today

Component	What it reads
store cache (storage/cache.go:192)	releases/<channel>/index-v2 every 60 min
store icon proxy (api/icon_proxy.go:23)	releases/stable/images/<app>-128.png
platform image proxy (backend/rest/proxy.go:39)	releases/<channel>/images/<app>-128.png
platform snap metadata (backend/snap/model/snap.go:36)	builds /rest/proxy/image?... URLs from snapd /v2/find responses

snapd is not in the loop. It's a passthrough — it returns whatever media[].url and description the backing store API hands it.

Today's app promote step

Each app's .drone.jsonnet (e.g. bitwarden/.drone.jsonnet) on the stable branch runs:

1. release publish — uploads snap binary + version files to S3
2. release promote -n <app> -a <arch> — copies releases/rc/<app>.<arch>.version to releases/stable/

Neither step pushes icon or metadata.

Migration shape

App side — extend syncloud-release promote (or add a subcommand) to also upload <app>-128.png and metadata.json (name, description, summary, ui, required) to s3://apps.syncloud.org/apps/<app>/metadata/. The icon can come from the snap's own snap/meta/gui/icon.png — no new file in the app repo. Each app's drone pipeline already calls release promote on stable, so no new CI step is needed; just a richer payload.

Store side (syncloud/store):

• storage/cache.go:192 — switch from a single index-v2 fetch to per-app metadata.json fetches
• api/icon_proxy.go:23 — redirect to the per-app path instead of releases/stable/images/
• Open question: how to know which apps exist without index-v2. Options:
  • S3 prefix listing
  • promote rewrites a small apps.json index
  • keep a minimal ID list in release/ (degenerate case of option 2)

Platform side (this repo):

• backend/rest/proxy.go:39 — rewrite proxy target to the new per-app path
• backend/snap/model/snap.go:36 — unchanged; still builds /rest/proxy/image?app=... URLs, only the upstream target moves

snapd — no changes.

Scope

Two files in store/, one file in platform/, one new upload command in store/cmd/release/. The hardest decision is the app-list mechanism, not the wiring.

Related repos

• syncloud/store
• syncloud/release (to be retired)
• syncloud/snapd (no change expected)