mAi: #7 - cloud-sync to Supabase Storage + imagen.images

Every successful imagen generate now (a) uploads the PNG to the private
imagen-generated bucket and (b) inserts a row into imagen.images, the
data plane the flexsiebels owner-mode viewer reads from.

Schema, RLS, indexes, bucket and PostgREST exposure landed via four
applied migrations on msupabase: imagen_schema_init,
imagen_schema_grants, imagen_storage_policies, imagen_pgrst_expose
(authenticator role-level ALTER + reload). Owner UUID for m:
ac6c9501-3757-4a6d-8b97-2cff4288382b — documented in the config sample.

Code: new internal/cloud/ package mirroring the internal/usage/ shape.
PostgREST POST against the imagen schema (Accept-Profile + Content-
Profile headers), Storage upload via PUT with x-upsert, retry on 5xx /
transport but not 4xx, owner_user_id required (the column is NOT NULL
and the read-side RLS policy needs it).

Wiring in cmd/imagen/generate.go: --no-cloud flag, output.cloud_sync
config knob (auto|on|off mirroring --preview), $IMAGEN_CLOUD_SYNC env
override. The hook reads the just-written PNG + sidecar from disk and
calls cloud.Sync; failures emit "imagen: cloud sync: <err>" to stderr
without changing exit code, so a Supabase blip never loses the artefact.
output.Outputs grew Date/Slug/Seed fields so storage_path mirrors the
local filename's prefix exactly (no UTC-vs-local drift).

Config: owner_user_id field added; sample comment points at the
auth.users lookup. imagen config validate warns on stderr when
cloud_sync is on/auto but owner_user_id is empty.

Tests: cloud_test.go covers happy path, retry-on-5xx, no-retry-on-4xx,
missing-owner-uuid, missing-date-or-slug, signed URL, and the partial-
success case where the upload landed but the DB insert failed.
generate_test.go covers the precedence chain for cloud-sync mode
resolution. Build + tests clean across the tree.

Real smoke against mRock: generation through flux-schnell-local writes
the local PNG + sidecar AND uploads to imagen-generated/2026-05-11/...
AND inserts into imagen.images. Signed URL round-trips the same bytes.
--no-cloud verified to skip both Storage and DB.

docs/architecture.md

@@ -16,6 +16,8 @@ upstream API. Each adapter only ever sees its own slice of `imagen.yaml`.
         │   internal/output     │   filename templating, sidecar
         │   internal/config     │   YAML loader, validation
         │   internal/preview    │   tmux-img window spawner
+        │   internal/cloud      │   Supabase Storage + imagen.images
+        │   internal/usage      │   mai.imagen_usage cost-tracking
         └──────────┬────────────┘
                    │
         ┌──────────▼────────────┐