Add a new scenario: firmware-update-success

[sepehr-safari]

Good First Issue

Add a new scenario firmware-update-success — a successful firmware update with no failures.

What to do

1. Create packages/toolkit/src/scenarios/__scenarios__/firmware-update-success.ts
2. Create a synthetic trace with: BootNotification → FirmwareStatusNotification (Downloaded) → FirmwareStatusNotification (Installed) → Heartbeat
3. Set expectedFailures: []
4. Import and register in packages/toolkit/src/scenarios/index.ts
5. Update scenario count in packages/toolkit/src/scenarios/index.test.ts and tests/external-fixture/test.mjs
6. Run ocpp-debugkit ci to verify all pass

Guidelines

• All data must be synthetic (use CS-SYNTHETIC-NNN for station IDs)
• Follow the pattern in existing scenario files (e.g., diagnostics-failure.ts)
• Add the assertions field with at least one assertion (e.g., no_failures)

Files to modify

• packages/toolkit/src/scenarios/__scenarios__/firmware-update-success.ts (new)
• packages/toolkit/src/scenarios/index.ts (register)
• packages/toolkit/src/scenarios/index.test.ts (update count)
• tests/external-fixture/test.mjs (update count)

How to claim

Comment "I'd like to work on this" and we'll assign it to you.