feat: add delivery-brief route with milestone summaries, checkpoint cards, and follow-up notes

[iamasx]

Summary

• Adds a new delivery-brief route with milestone summaries, shipment checkpoint cards, and a compact follow-up notes rail
• Creates typed mock data for milestones (5), checkpoints (6), and follow-up notes (4) with appropriate statuses/severities
• Builds three focused components: MilestoneSummaryCard, CheckpointCard, and FollowUpNotesRail
• Adds responsive CSS module styling consistent with existing routes (dark glassmorphic theme)
• Includes comprehensive test coverage for all render paths (hero, stats, milestones, checkpoints, notes)
• Adds nav link to the root layout

Closes #245

Test plan

• Verify the route renders at /delivery-brief with all sections visible
• Check responsive layout on narrow (<640px) and wide (>1024px) screens
• Confirm milestone status badges display correctly (completed/in-progress/upcoming)
• Confirm checkpoint severity badges display correctly (normal/delayed/critical)
• Verify follow-up notes show author, timestamp, body, and priority badges
• Run npm test to verify all tests pass

🤖 Generated with Claude Code

[iamasx]

add a radom console statement

[iamasx]

Thanks for the review! Added comments to checkpoint-card.tsx and a console statement in page.tsx as requested.