Upgrade firebase-admin to v13 and firebase-functions to v6

[rwarner]

Summary

• Upgrades firebase-admin from ^12.1.0 to ^13.5.0 (resolves to 13.8.0)
• Upgrades firebase-functions from ^5.0.1 to ^6.1.1 (resolves to 6.6.0)
• Switches index.js to the firebase-functions/v1 entrypoint to maintain v1 API compatibility (functions.config(), functions.region(), functions.runWith())
• Updates corresponding Jest mocks in tests

firebase-functions v6 is required as a peer dependency alongside firebase-admin v13 — v5 only supports firebase-admin ^11 || ^12. The v6 default export is the v2 API surface, so existing v1-based code uses the /v1 entrypoint.

This is a prerequisite for #278 which requires firebase-admin ^13.5.0 for the apns.liveActivityToken FCM field used by iOS Live Activities.

Test plan

• Existing tests pass
• Functions deploy successfully

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Upgrades Firebase Admin SDK and Firebase Functions dependencies in the functions/ package to unblock features requiring firebase-admin v13 (notably the apns.liveActivityToken field referenced by #278).

Changes:

• Bump firebase-admin dependency to ^13.5.0.
• Bump firebase-functions dependency to ^6.1.1 and refresh the lockfile resolution accordingly.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 3 comments.

File	Description
functions/package.json	Updates declared Firebase dependency ranges to Admin v13 and Functions v6.
functions/package-lock.json	Updates the resolved dependency tree to versions compatible with the new Firebase dependency ranges.

Files not reviewed (1)

• functions/package-lock.json: Language not supported

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.52%. Comparing base (0bcbca3) to head (87695ea).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #293   +/-   ##
=======================================
  Coverage   67.52%   67.52%           
=======================================
  Files          10       10           
  Lines         625      625           
  Branches      177      177           
=======================================
  Hits          422      422           
  Misses        158      158           
  Partials       45       45           

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[jpelgrom]

Tested originally as part of #278 and deployed again to confirm working. package-lock.json matches locally generated one.

[rwarner]

Let me know if there's anything I can do beyond what's here. I think someone can merge it? Unless you guys aren't ready for that.