[Fix]: Ensure JWT sub is a string

[EspressoTrip-v2]

Background

We previously assumed the JWT sub claim was always a string; however, it can also be a boolean, object, or array.

Issue

• Client analytics fails when sub is not a string.
• Other code paths that rely on context.user_id or token payload string semantics may also be affected.

Fix

Normalize sub immediately after JWT verification (in KeyStore.verifyJwt): keep strings as-is, use JSON.stringify for everything else, and use the normalized value for context.user_id and token_payload.

Impact of the fix

• request.user_id() / auth.user_id() now consistently return a string.
• String sub values are unchanged; non-string sub values are normalized with JSON.stringify.
• Sync rules that expect string IDs continue to behave as before; rules that assume strict non-string typing should be reviewed.

[changeset-bot]

🦋 Changeset detected

Latest commit: e374a58

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

This PR includes changesets to release 12 packages

Name	Type
@powersync/service-core	Patch
@powersync/service-core-tests	Patch
@powersync/service-module-core	Patch
@powersync/service-module-mongodb-storage	Patch
@powersync/service-module-mongodb	Patch
@powersync/service-module-mssql	Patch
@powersync/service-module-mysql	Patch
@powersync/service-module-postgres-storage	Patch
@powersync/service-module-postgres	Patch
@powersync/service-image	Patch
test-client	Patch
@powersync/service-schema	Patch

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