feat: simple typed accessors for results/outputs + task ResultBuilder

[ndizazzo]

This PR introduces a simplified, ergonomic API for fetching data from actions and tasks, and updates docs/tests accordingly.

Highlights:

• GlobalContext typed helpers:
  • ActionResultAs[T], TaskResultAs[T]
  • ActionOutputFieldAs[T], TaskOutputFieldAs[T]
  • EntityValue / EntityValueAs[T]
• Generic ResolveAs[T] for parameter-based typed resolution
• Task.ResultBuilder support to emit a structured task result
• Tests covering typed helpers and ResolveAs
• Documentation updates:
  • Reorganized to emphasize simple typed approach first
  • Added examples for action/task results and outputs

All tests pass (go test ./...).

[codecov]

Codecov Report

❌ Patch coverage is 55.29954% with 194 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.65%. Comparing base (5a30241) to head (99fb851).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
parameters.go	51.42%	103 Missing and 16 partials ⚠️
action.go	52.94%	40 Missing and 16 partials ⚠️
task.go	72.85%	17 Missing and 2 partials ⚠️

❌ Your patch status has failed because the patch coverage (55.29%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (74.65%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #13      +/-   ##
==========================================
- Coverage   75.29%   74.65%   -0.65%     
==========================================
  Files          47       48       +1     
  Lines        6096     6332     +236     
==========================================
+ Hits         4590     4727     +137     
- Misses       1236     1312      +76     
- Partials      270      293      +23     

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