feat(audit): MVP output - AUDIT_REPORT.md only, move stale to _stale/

MVP pipeline simplification:
- render_rollups() now produces ONLY summary.md + AUDIT_REPORT.md
- run_audit() now produces only per-aggregate .md (no .dsl/.tree)
- New src/code_path_audit_gen.py generates the single coherent report

Stale artifacts moved to _stale/ subdirectory (preserved for history):
- 13 per-aggregate .dsl files (redundant with .md)
- 13 per-aggregate .tree files (redundant with .md)
- 9 old top-level rollups (cross_audit_summary, decomposition_matrix,
  candidates, field_usage, call_graph, hot_paths, dead_fields,
  ssdl_analysis, organization_deductions - all superseded by sections
  inlined in AUDIT_REPORT.md)
- _stale/README.md explains what happened

Meta-audit updated to check .md files (14 required H2 sections per
aggregate) instead of .dsl files. 0 violations on 10 real profiles.

Tests: 131 passing. New MVP report: 5000+ lines.

scripts/audit_code_path_audit_coverage.py

@@ -14,20 +14,20 @@ import sys
 from pathlib import Path
 
 REQUIRED_SECTIONS: tuple[str, ...] = (
- "aggregate_kind",
- "memory_dim",
- "producers",
- "consumers",
- "access_pattern",
- "access_pattern_evidence",
- "frequency",
- "frequency_evidence",
- "result_coverage",
- "type_alias_coverage",
- "cross_audit_findings",
- "decomposition_cost",
- "optimization_candidates",
- "is_candidate",
+ "Pipeline summary",
+ "Producers",
+ "Consumers",
+ "Field access matrix",
+ "Access pattern",
+ "Frequency",
+ "Result coverage",
+ "Type alias coverage",
+ "Cross-audit findings",
+ "Decomposition cost",
+ "Struct shape",
+ "Optimization candidates",
+ "Verdict",
+ "Evidence appendix",
 )
 
 
@@ -46,17 +46,15 @@ def main() -> int:
   return 1
  violations: list[str] = []
  files_checked = 0
- for dsl_path in sorted(aggregates_dir.glob("*.dsl")):
-  content = dsl_path.read_text(encoding="utf-8")
-  if " true is-candidate" in content:
+ for md_path in sorted(aggregates_dir.glob("*.md")):
+  content = md_path.read_text(encoding="utf-8")
+  if "**Is candidate:** True" in content:
    continue
   files_checked += 1
   for section in REQUIRED_SECTIONS:
-   marker_prefix = f"\\ === {section}"
-   if marker_prefix not in content:
-    violations.append(f"{dsl_path.name}: missing section '{section}'")
-  if " cross-audit-findings" not in content:
-   violations.append(f"{dsl_path.name}: missing 'N cross-audit-findings' count line")
+   marker = f"## {section}"
+   if marker not in content:
+    violations.append(f"{md_path.name}: missing section '{section}'")
  if violations:
   print(f"Meta-audit: {len(violations)} violations ({files_checked} real profiles checked)")
   for v in violations: