[build-tools] Use production mode for app config, prebuild, and Expo Doctor

[ramonclaudio]

Part of DVT-119. Follow-up to expo/expo#48554 and expo/expo#48741. Related to expo/expo#48839, expo/expo#48845, and expo/expo#48882.

Why

EAS Build can use a user-defined NODE_ENV when it reads app config or runs Expo commands. This can make it load a different .env file for the same build.

How

EAS Build now uses production mode when it reads app config or runs prebuild and Expo Doctor.

EAS Build sets NODE_ENV for older Expo versions and the @expo/config fallback. Current Expo tools receive the same mode through EXPO_CONFIG_MODE.

Dependency installs still use the user's original env.

Test Plan

• Ran all @expo/build-tools tests
• Ran corepack yarn typecheck
• Ran corepack yarn build
• Ran corepack yarn lint
• Ran corepack yarn fmt:check
• Ran corepack yarn actionlint
• Ran the @expo/build-tools prepack check

[linear-code]

DVT-119

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.41%. Comparing base (067c0e5) to head (c6fffa5).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4180      +/-   ##
==========================================
+ Coverage   63.32%   63.41%   +0.10%     
==========================================
  Files        1025     1027       +2     
  Lines       46786    46825      +39     
  Branches     9865     9817      -48     
==========================================
+ Hits        29624    29691      +67     
- Misses      15707    17033    +1326     
+ Partials     1455      101    -1354     

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[github-actions]

✅ Thank you for adding the changelog entry!