feat(memory): add standalone atomic files to memory-index routing

Issue #307: ADR-017 Phase 3 completion

Standalone atomic files added (per ADR-017 small file exception):
- skills-regex, skills-roadmap, skills-governance
- skills-dorny-paths-filter-checkout-requirement
- skills-edit, skills-pr-validation-gates
- skills-process-workflow-gaps, skills-cva-refactoring
- skills-agent-workflow-phase3

Final stats: 30 domain indexes, 194 indexed files
Validation: PASSED

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: rjmurillo-bot

.serena/memories/memory-index.md

@@ -30,6 +30,15 @@
 | git hook pre-commit autofix cross-language grep TOCTOU | skills-git-hooks-index |
 | protocol blocking gate RFC MUST verification template legacy | skills-protocol-index |
 | retrospective learning session failure | retrospective-2025-12-17, retrospective-2025-12-18 |
+| regex pattern match escape lookahead anchor quantifier | skills-regex |
+| roadmap epic priority strategic vision business value | skills-roadmap |
+| governance agent consolidation design principle overlap | skills-governance |
+| dorny paths-filter checkout base ref PR changes | skills-dorny-paths-filter-checkout-requirement |
+| edit file read search replace text operation | skills-edit |
+| pr validation gate status check blocker merge | skills-pr-validation-gates |
+| process workflow gap missing capability root cause | skills-process-workflow-gaps |
+| cva refactoring variant consolidation template generate | skills-cva-refactoring |
+| phase3 agent skill session handoff template verification | skills-agent-workflow-phase3 |
 
 ## User Constraints (MUST READ)