BJ-0: Add 'jira' to platform unions + audit 'github' hardcodes#

Problem#

The platform union types in dispatch-event.dto.ts and tenant-config.interface.ts did not include 'jira', blocking Wave 1 of the Atlassian integration epic from routing Jira-sourced events through the pipeline.

Task / Link#

Closes #540 — Wave 0 serial blocker for Atlassian integration epic #539

Changes#

• Added 'jira' to DispatchEventParams.platform union in src/webhook/dto/dispatch-event.dto.ts
• Added 'jira' to DispatchEvent.platform union in src/webhook/dto/dispatch-event.dto.ts
• Added 'jira' to TenantConfig.platform union in src/tenant/tenant-config.interface.ts

Notes#

• PR targets rc/atlassian-integration (the integration branch), not master
• Pre-existing 'github' literals in tenant-config.service.ts (default config value) and tenant.module.ts (default provider name) are configuration values, not equality branches — confirmed out of audit scope

Grep audit — no platform === 'github' equality branches in audited paths:

All four paths (src/dispatch/, src/phase-router/, src/tenant/, src/invoke/) are clean.

Testing#

• node_modules/.bin/tsc --noEmit → 0 errors
• npm run lint → passed (zero warnings)
• npm run test → 834 tests passed, 53 suites, 0 failures