fix(proxy): restore pusher email from the token cache

[sankalpsthakur]

Summary

checkUserPushPermission looks up the pusher by action.userEmail. After #1604, resolveUserFromToken maps a GitHub PAT to a GitProxy user on a cold cache, but the token cache only stored the username. On a cache hit the username was overwritten and the last-commit committer email from parsePush was left in place, so the permission check ran against the wrong user (the remaining path on #1400 that @jescalada reproduced). Tag pushes never ran resolveUserFromToken at all.

• Cache { username, email } and restore both on hit
• Run resolveUserFromToken first on the tag-push chain, same as branch pushes

Does not close #1400: GHES / non-github.com providers and unmatched gitAccount are unchanged.

Validation

• npx vitest run test/processors/resolveUserFromToken.test.ts test/chain.test.ts test/testCheckUserPushPermission.test.ts
• 58 passed (30 + 25 + 3)

Related to #1400

AI/LLM disclosure

• AI coding tools (including Grok and/or Codex agent-assisted editing) were used to help draft or modify code and this PR description.
• I reviewed the complete change, understand the reasoning, and ran the reported local tests before submitting.
• This submission is original work of authorship under the project CLA / contributor terms; AI output was not pasted unreviewed.

[netlify]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.06%. Comparing base (4ccae8a) to head (23be2ce).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1713   +/-   ##
=======================================
  Coverage   86.05%   86.06%           
=======================================
  Files         101      101           
  Lines        5571     5574    +3     
  Branches      995      997    +2     
=======================================
+ Hits         4794     4797    +3     
  Misses        526      526           
  Partials      251      251           

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