How does CEL handle a large, frequently-mutated text field?

[brianorwhatever]

Part of #227

Question

How does Originals / CEL handle a large, frequently-mutated text field across events?

Factual groundwork for the sealing decision. Needed:

• How AssetEnvelope events are structured, and what the size cost per event actually is (the schema comment cites ~1.8KB at genesis, growing per event).
• Whether CEL supports content hashes / references rather than inline content, so prose can be committed to without being embedded.
• What did:webvh publishing does to the envelope, and whether the log has a practical size ceiling.
• Whether anything in the Originals SDK already models a mutable document as opposed to an append-only item log.

Sources: the @originals/sdk package in node_modules, convex/originals.ts, convex/listEnvelopes usage, and the Originals 3.0.0-next.0 upgrade in #223.

Resolve with a /research subagent; capture findings on a throwaway research/cel-mutable-content branch and link them here.