Introduces the data layer for the Workload refactor (see
docs/plans/workload-refactor.md): three new tables and store
methods, no behavior changes elsewhere yet.
- workloads: unifying primitive over Project/Stack/StaticSite,
paired via UNIQUE(kind, ref_id). Notification + webhook config
hosted here so it lives in one place across kinds.
- containers: normalized index of every Tinyforge-managed
container with first-class subdomain/proxy_route_id/npm_proxy_id
columns (heavily queried by ListProxyRoutes / stale detection).
- apps: optional grouping of workloads; schema only, no UI in v1.
Foundation only — deployer surgery, reconciler, and consumer
switchover land in the next commit.
