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/_dintel-shared/src/dintel/excel.py

@@ -0,0 +1,71 @@
+"""Excel utilities for D.intelligence branded spreadsheets."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from openpyxl import Workbook
+from openpyxl.styles import Font, PatternFill, Alignment, Border, Side
+
+from dintel.brand import (
+    BRAND_NAME,
+    HEX_PRIMARY,
+    HEX_SECONDARY,
+    HEX_ACCENT,
+    HEX_TEXT,
+)
+
+# ── Style Constants ─────────────────────────────────────────────
+HEADER_FILL = PatternFill(start_color=HEX_PRIMARY.lstrip("#"), end_color=HEX_PRIMARY.lstrip("#"), fill_type="solid")
+HEADER_FONT = Font(name="Arial", size=10, bold=True, color="FFFFFF")
+SUBHEADER_FILL = PatternFill(start_color=HEX_SECONDARY.lstrip("#"), end_color=HEX_SECONDARY.lstrip("#"), fill_type="solid")
+SUBHEADER_FONT = Font(name="Arial", size=10, bold=True, color="FFFFFF")
+ACCENT_FONT = Font(name="Arial", size=10, bold=True, color=HEX_ACCENT.lstrip("#"))
+BODY_FONT = Font(name="Arial", size=10, color=HEX_TEXT.lstrip("#"))
+THIN_BORDER = Border(
+    left=Side(style="thin"),
+    right=Side(style="thin"),
+    top=Side(style="thin"),
+    bottom=Side(style="thin"),
+)
+CENTER_ALIGN = Alignment(horizontal="center", vertical="center", wrap_text=True)
+LEFT_ALIGN = Alignment(horizontal="left", vertical="center", wrap_text=True)
+RIGHT_ALIGN = Alignment(horizontal="right", vertical="center")
+
+
+def create_branded_workbook(title: str = "D.intelligence") -> Workbook:
+    """Create an openpyxl Workbook with brand defaults."""
+    wb = Workbook()
+    wb.properties.title = title
+    wb.properties.creator = BRAND_NAME
+    return wb
+
+
+def style_header_row(ws, row: int = 1, col_start: int = 1, col_end: int = 10) -> None:
+    """Apply header styling to a row."""
+    for col in range(col_start, col_end + 1):
+        cell = ws.cell(row=row, column=col)
+        cell.fill = HEADER_FILL
+        cell.font = HEADER_FONT
+        cell.alignment = CENTER_ALIGN
+        cell.border = THIN_BORDER
+
+
+def style_body_cell(cell, align: str = "left") -> None:
+    """Apply body styling to a cell."""
+    cell.font = BODY_FONT
+    cell.border = THIN_BORDER
+    if align == "center":
+        cell.alignment = CENTER_ALIGN
+    elif align == "right":
+        cell.alignment = RIGHT_ALIGN
+    else:
+        cell.alignment = LEFT_ALIGN
+
+
+def save_workbook(wb: Workbook, output_path: str | Path) -> Path:
+    """Save workbook and return the path."""
+    output_path = Path(output_path)
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+    wb.save(str(output_path))
+    return output_path