[steps][4/4] Resolve composite function outputs

[sswrk]

Why

This PR stack adds local composite functions for EAS workflows. A function.yml declares outputs: with templated values, and the caller should read them as ${{ steps.setup.outputs.version }}, where setup is the id of the calling step.

After the previous PRs, data flows into a composite function (inputs, env) but nothing flows back out. This PR closes that loop.

How

For a composite function that declares outputs:, CompositeFunctionExpander appends a synthetic function step after the inner steps, reusing the caller's step id.

• The step runs with if: ${{ always() }}
• Output values are interpolated against the composite-function-local step namespace

Test Plan

Added outputs unit tests.

[linear-code]

ENG-22387

[sswrk]

• [eas-cli] Validate legacy command/path local functions referenced from workflows #4098
• [build-tools] Load legacy command/path local functions and resolve module paths #4097
• [steps] Expand legacy command/path local functions to a single build step #4096
• [eas-build-job] Accept legacy command/path custom function shape in function.yml #4095
• [eas-cli] Validate local composite functions referenced from workflow hooks #4064
• [build-tools] Load composite function catalogs for hook steps #4063
• [steps] Support local composite functions in hook steps #4062
• [steps] Unify the default gating of steps with no if: across steps, composite scopes, and hooks #4061
• [eas-cli] Validate local composite functions in workflow files #3931
• [build-tools] Load local composite function catalog at build runtime #3930
• [steps][4/4] Resolve composite function outputs #4015 👈 (View in Graphite)
• [steps][3/4] Interpolate composite function inputs #4014
• [steps][2/4] Expand composite function references into build steps #3929 : 1 other dependent PR (#4013 )
• [steps][1/4] Add isCompositeFunctionPath and reject local composite functions in custom builds #3956
• [eas-build-job] Add local composite function schema #3928
• main

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.48%. Comparing base (a8e8c79) to head (562532f).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4015      +/-   ##
==========================================
+ Coverage   61.29%   61.48%   +0.19%     
==========================================
  Files         977      978       +1     
  Lines       43687    43839     +152     
  Branches     9186     9217      +31     
==========================================
+ Hits        26774    26948     +174     
+ Misses      15465    15443      -22     
  Partials     1448     1448              

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[claude]

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[github-actions]

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