Fix ref_group attribute overrides dropped in span_refinements

[Copilot]

span_refinements using ref_group to include an attribute_group silently drop per-attribute overrides (e.g. note). The same group included from a regular spans entry preserves overrides correctly.

Root cause: In registry.rs, include_groups resolution was gated behind an else if on the extends branch. Since refinements always set extends, their include_groups (populated from ref_group) were never processed.

# Both pull the same group, but only the span preserves note: OVERRIDE_NOTE
spans:
  - type: my.regular
    attributes:
      - ref_group: my.group  # ✅ OVERRIDE_NOTE preserved

span_refinements:
  - id: my.refinement
    ref: my.base
    attributes:
      - ref_group: my.group  # ❌ OVERRIDE_NOTE dropped, got REGISTRY_NOTE

Changes:

• Collect include_groups inside the extends block and pass all parent attribute sources together to resolve_inheritance_attrs_unified, so both inheritance and group inclusion are resolved in a single pass
• The standalone else if branch for include_groups (no extends) is unchanged
• Updated registry-test-v2-4-refinements to cover ref_group with a note override in both a regular span and a span refinement, asserting both resolve identically

[codecov]

Codecov Report

❌ Patch coverage is 64.28571% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.4%. Comparing base (69132ef) to head (2d35a49).

Files with missing lines	Patch %	Lines
crates/weaver_resolver/src/registry.rs	64.2%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1407     +/-   ##
=======================================
- Coverage   82.4%   82.4%   -0.1%     
=======================================
  Files        120     120             
  Lines      10092   10105     +13     
=======================================
+ Hits        8320    8327      +7     
- Misses      1772    1778      +6     

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