refactor: reorganize skill numbering, remove obsolete skills, rename shared libs

- Rename: 00→80 claude-settings-optimizer, 88→79 dintel-skill-update,
  92→81 mac-optimizer, 93→82 tui-design-template
- Rename: dintel-shared → _dintel-shared (consistent with _ourdigital-shared)
- Remove: 61-gtm-manager, 62-gtm-guardian (obsolete), 99_archive
- Update all dintel-* skill refs (114 occurrences across 31 files)
- Sync README.md, CLAUDE.md, AGENTS.md with new structure

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

custom-skills/73-dintel-quotation-mgr/code/scripts/generate_quotation.py

@@ -2,14 +2,14 @@
 D.intelligence Quotation Generator
 Agent #73 - dintel-quotation-mgr
 
-Generates branded Excel .xlsx quotation files using dintel-shared utilities.
+Generates branded Excel .xlsx quotation files using _dintel-shared utilities.
 This is a stub script -- extend with full implementation as needed.
 
 Usage:
     python generate_quotation.py --client "고객사명" --modules A3,T6 --output ./output/
 
 Dependencies:
-    - dintel-shared (../../dintel-shared/)
+    - _dintel-shared (../../_dintel-shared/)
     - openpyxl
 """
 
@@ -186,13 +186,13 @@ def build_quotation(
 
 
 # ---------------------------------------------------------------------------
-# Excel generation (stub -- requires openpyxl and dintel-shared)
+# Excel generation (stub -- requires openpyxl and _dintel-shared)
 # ---------------------------------------------------------------------------
 
 def generate_xlsx(draft: QuotationDraft, output_dir: Path) -> Path:
     """Generate branded .xlsx quotation file.
 
-    TODO: Implement full branded workbook using dintel-shared/src/dintel/excel.py.
+    TODO: Implement full branded workbook using _dintel-shared/src/dintel/excel.py.
     This stub creates a basic workbook structure.
     """
     try: