Update specs to match implementation

Addresses spec drift items #3, 5, 6, 7, 8, 9, 10, 11, 12 from #147:

- transactional-emails: Resend → Nodemailer + SMTP
- infrastructure: CX21 → cx23
- secret-management: single secrets.env → split app/infra files
- brouter-integration: 5s failover delay → instant via clientID election
- brouter-integration: 2 profiles → 5 (trekking, fastbike, safety, shortest, car)
- observability: add version field to health response
- observability: add brouter_request_duration_seconds metric
- planner-session: remove 30-day max ceiling (not enforced)
- shared-packages: clarify map package scope vs planner-specific features

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openspec/specs/planner-session/spec.md

@@ -45,7 +45,7 @@ The Planner SHALL persist Yjs session state to PostgreSQL so that sessions survi
 - **THEN** reconnecting clients recover the full session state from PostgreSQL
 
 ### Requirement: Session expiry
-The Planner SHALL automatically expire sessions after a configurable period of inactivity (default: 7 days, max: 30 days).
+The Planner SHALL automatically expire sessions after a configurable period of inactivity (default: 7 days, no hard ceiling enforced).
 
 #### Scenario: Session expires
 - **WHEN** no edits are made to a session for 7 days