fix(bindings-typescript): support cross-bundle Range instances in index scans (#6299) - #6350

Summary

Fixes #6299.

When using spacetimedb/server/test-utils or module code bundled across entrypoints, filtering or deleting through a table index using a Range instance failed because range instanceof Range evaluated to false.

dist/server/test-utils/index.mjs and dist/server/index.mjs are separate bundles, each inlining its own copy of Range. Consequently:

1. range instanceof Range evaluates to false across bundles.
2. The runtime falls back to serializing the Range object as a single point.
3. On number columns, index scans match no rows. On BigInt-backed columns (like Timestamp), the point serializer throws TypeError: Cannot convert undefined to a BigInt.

Solution

1. Added Symbol.for('spacetimedb.Range') brand to Range.prototype and added Range.isRange(val) / exported isRange(val) predicate.
2. In crates/bindings-typescript/src/server/runtime.ts, replaced instanceof Range checks in single-column index filter/delete and multi-column index scan paths with isRange(...).
3. Added unit and regression tests in crates/bindings-typescript/tests/index_prefix_filter.test.ts verifying that cross-bundle Range instances work seamlessly for both single-column and multi-column btree index filters and deletes.

Verification

• Ran vitest run tests/index_prefix_filter.test.ts: all 11 tests passed.
• Ran tsc -p tsconfig.build.json: type check passed.
• Ran prettier --check on modified files: passed.