Traverse overlapping constraint dependencies

[iangneal]

Summary

Makes constraint-dependency traversal overlap-aware on top of #650. This is PR 4 of 6 in the stacked series.

Related issues

No standalone issue; depends on #650.

Changes

• Track pairwise dependency edges separately from broad equivalence classes.
• Traverse overlapping aggregate ranges transitively and narrow them to queried concrete elements.
• Include ancestor constraints while filtering structurally incompatible aggregate alternatives.
• Preserve dependency edges through graph copying, translation, and interprocedural merging.
• Add regressions proving a range constrains included elements while leaving omitted elements unconstrained.
• Add changelogs/unreleased/codex__circom-analysis-4-overlap-cdg.yaml.

Testing

• git diff --check
• Focused overlap-aware CDG regressions
• nix build -L on this exact stacked commit (371 lit tests plus the full unit/CAPI suite passed)

Submission checklist

• If I am an external contributor, this PR has a linked issue marked approved; otherwise, this does not apply.
• I added or updated tests for all relevant behavior, or explained above why tests are not needed.
• I updated the relevant TableGen or other documentation, or explained above why documentation is not needed.
• I added a changelog entry describing user-visible changes. (create-changelog in the Nix development shell creates a template.)
• I enabled Allow edits from maintainers if this PR comes from a fork.

AI assistance

• No AI tools contributed to this PR.
• AI tools contributed to this PR.

Tools used: OpenAI Codex.

How the tools contributed: Codex helped partition the original working-tree change, preserve dependency ordering, add focused regressions and changelog entries, and prepare this draft PR.

How I verified the contribution: Reviewed the isolated diff and ran git diff --check, the focused analysis regressions through the project test suite, and nix build -L on this exact commit.

[github-actions]

Test Results

  2 files  ±0    2 suites  ±0   11m 1s ⏱️ + 2m 56s
371 tests ±0  367 ✅ ±0  4 💤 ±0  0 ❌ ±0 
742 runs  ±0  734 ✅ ±0  8 💤 ±0  0 ❌ ±0 

Results for commit aafd711. ± Comparison against base commit 305824f.

♻️ This comment has been updated with latest results.