Make the data sync export available on all plans, and usable from components

Convex already keeps an ordered log of every write, the one behind the data sync export (/data/sync). It answers "what changed since T?" in commit order. Today it needs a Pro plan and a deployment:data:view credential. Components that sync, cache, index or replicate data need exactly this. Without it, they either wrap every mutation, which misses dashboard edits, imports and other code, or re-run queries, which re-reads everything after a client has been offline. It doesn't need a plan gate. The log already exists for every deployment, and reading it is ordinary metered work: function calls, reads and bandwidth. Gating it pushes free-tier apps toward query replay, which uses more compute for the same result. It would also make component setup much cleaner. Today a component would have to ask each app developer to upgrade and paste a credential into the component's environment. A function-level API, or an automatically scoped read-only credential, would let a component just work after app.use(...).