feat: Ingredient API to save snapshot and rehydrate later

[sorohan]

This exposes functionality from the Rust SDK to create an ingredient from a file, serialize it to a snapshot for persistence, and later restore it without needing the original asset bytes.

This enables workflows where ingredients need to be cached and restored later for signing.

Usage:

// Create & persist ingredient
const ref = await c2pa.ingredient.fromBlob(format, blob);
const snapshot = await ref.toSnapshot();
await save(snapshot); // save the snapshot somewhere

// Restore & use
const snapshot = load(); // load the snapshot from somewhere
const ref = await c2pa.ingredient.fromSnapshot(snapshot);
await builder.addIngredientFromRef(ref, 'componentOf');

Closes #70

[changeset-bot]

🦋 Changeset detected

Latest commit: df22751

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@contentauth/c2pa-wasm	Minor
@contentauth/c2pa-web	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR