Move routing table, emit(), and is_enterprise_telemetry_enabled() from
enterprise/telemetry/gateway.py into core/telemetry/gateway.py so both
CE and EE share one code path. The ce_eligible flag in CASE_ROUTING
controls which events flow in CE — flipping it is the only change needed
to enable an event in community edition.
- Delete enterprise/telemetry/gateway.py (class-based singleton)
- Create core/telemetry/gateway.py (stateless functions, no shared state)
- Simplify core/telemetry/__init__.py to thin facade over gateway
- Remove TelemetryGateway class and get_gateway() from ext_enterprise_telemetry
- Single-source is_enterprise_telemetry_enabled in core.telemetry.gateway
- Fix pre-existing test bugs (missing dify.event.id in metric handler tests)
- Update all imports and mock paths across 7 test files
