fix_stack_main: consolidated closure + validation evidence

[jmsexton03]

Summary

Consolidated fix-stack closure PR for fix_stack_main.

• Canonical branch: fix_stack_main
• Tip commit: 73f37cf9e86dc86c4e19c83621bba10d1be63f84 (short: 73f37cf9)
• Scope: all 19 slice finding streams reconciled on stacked lineage.
• What was added/changed in this closure cycle:
  • reconciled all 19 slice finding streams into a single canonical fix stack (open_findings = 0)
  • resolved the full-run failure cluster (input-writer signature compatibility, sweep polling behavior, ERF fallback contract, FAISS query behavior)
  • normalized matrix semantics and aligned slice terminal statuses with reconciled closure state
  • produced canonical validation evidence bundle (targeted rerun + unit/full/quality/integration-ladder outcomes)
• Workstreams (topic-level):
  • workflow graph/node routing and handler continuity fixes
  • service-layer robustness updates (runner/input-writer/orchestrator/fallback paths)
  • schema/index/manifest compatibility and provenance consistency handling
  • visualization and benchmark/tooling behavior normalization
  • validation/reporting artifact consolidation for publish readiness

Closure Status

• Matrix status: open_findings = 0 and all slices marked fixed_on_stacked_branch.
• Findings reconciliation: artifacts/integration/findings_reconciliation.{json,md}
• Branch remap impact: artifacts/integration/fix_branch_remap_impact.md

Validation Evidence

Run bundle: artifacts/integration/reports/fix_stack_main_20260318_034847/

• Fast targeted rerun: 10 passed, 3 warnings
• Unit gate: 1663 passed, 31 skipped, 3 warnings
• Full suite: 1813 passed, 78 skipped, 10 xfailed, 11 warnings
• Quality gate: 20 passed, 1 skipped, 5 warnings
• Integration ladder: 47 passed, 36 skipped, 92 deselected, 1 xfailed, 7 warnings

Tracked JUnit evidence:

• artifacts/integration/reports/fix_stack_main_20260318_034847/unit.junit.xml
• artifacts/integration/reports/fix_stack_main_20260318_034847/full.junit.xml

Notes

• This PR intentionally attributes fixes to canonical stacked lineage rather than one-PR-per-slice.
• Publish/open actions were deferred during local closure; this body is prepared for networked publish phase.