PyodideBridge dispose should reset initPromise to allow re-init

[bbopen]

Summary

PyodideBridge.dispose() sets this.py to undefined but leaves initPromise intact. Subsequent init() calls return the resolved promise without reinitializing, leaving py undefined and causing failures.

Failure mode

• Create bridge → init() → dispose() → init() again.
• ensureReady() returns the existing initPromise and does not re-run initialization.
• call/instantiate fail with "Pyodide not initialized".

Evidence

• src/runtime/pyodide.ts dispose() and ensureReady().

Proposed fix

• Clear initPromise in dispose().
• Consider resetting any other state that blocks re-init.

Acceptance criteria

• After dispose(), a new init() reinitializes pyodide successfully.
• Add a test covering dispose → re-init flow.

[bbopen]

Resolved by PR #150. BoundedContext.dispose() properly resets state to 'disposed'.