Avoid decoding activity payloads for metadata projections

[rmcdaniel]

Change

Adds an opt-in metadata-only RunActivityView mode that omits argument/result fields without downloading external objects. Summary, wait, task, and parallel-completion metadata consumers use it; normal decoded views retain their default behavior and typed-history authority.

Fixes #490 when qualified and released. Paired with durable-workflow/server#142; this PR is not release-ready yet.

Checked

• Focused metadata cold-model reload plus activity outcome/history-role tests: 18 tests, 67 assertions, passing with SQLite file storage and isolated Redis.
• Changed-file ECS and PHPStan pass.
• Candidate combined with Server draft fixes: actual Apache HTTP upload/fetch plus two concurrent 64 MiB workflow result completions and a 64 MiB activity result completion/inspection pass at unchanged PHP 128 MiB and HTTP-container 176 MiB limits.
• Full CI, remaining transport scenarios, cold HTTP recovery, and package publication still pending.

Initial in-memory SQLite multi-class test execution hit a harness missing-table problem; the same tests pass with a persistent disposable SQLite file. No production changes.

[rmcdaniel]

The public PR checks passed at 9778c54. Full source qualification is now running through the existing build workflow: https://github.com/durable-workflow/workflow/actions/runs/34205502106.

Additional regression evidence:

• The new metadata test fails when only RunSummaryProjector is restored to the target revision: one external read occurs where zero is required. This confirms the regression catches the actual eager-fetch boundary.
• Combined with Server PR Automation workflow with drag and drop #142, actual Apache requests completed two concurrent 64 MiB encoded workflow results and a 64 MiB standalone activity input/result under the unchanged 128 MiB PHP heap limit and a 176 MiB HTTP-container limit, with no cgroup OOM or OOM kill.
• After restarting both Server and MySQL, all completed results and reference hashes survived; an independent read-only consumer decoded the full values with official Avro.
• The combined Server Feature suite passed: 2,058 tests / 41,626 assertions, with 6 deprecations and 3 skips. A subsequent focused scheduled-activity reference test passed separately.

This is composite unreleased source validation, not a published-package or production claim. Full engine CI and package publication remain before the Server dependency can be updated.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.85%. Comparing base (af1b743) to head (9778c54).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #491      +/-   ##
==========================================
- Coverage   87.86%   87.85%   -0.01%     
==========================================
  Files         460      460              
  Lines       62953    62958       +5     
==========================================
+ Hits        55311    55313       +2     
- Misses       7642     7645       +3     

Flag	Coverage Δ
v2	87.85% <100.00%> (-0.01%)	⬇️

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