Wire INTEGRATION_SECRET into docker-compose and CI; archive komoot-import

- Add INTEGRATION_SECRET to journal service in docker-compose.yml with
  :? guard so a missing value fails loudly at compose-up time
- Add INTEGRATION_SECRET to E2E test step in ci.yml via GitHub secret
  (unit tests already set their own value in the test file)
- Archive openspec/changes/komoot-import → archive/2026-05-23-komoot-import
- Sync delta specs: new openspec/specs/komoot-import/spec.md,
  updated openspec/specs/route-management/spec.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -256,6 +256,7 @@ jobs:
         env:
           BROUTER_URL: http://localhost:17777
           E2E: "true"
+          INTEGRATION_SECRET: ${{ secrets.INTEGRATION_SECRET }}
 
       - name: Playwright job summary
         if: ${{ !cancelled() }}