feat: add D.intelligence Agent Corps (9 skills + shared infra)

Add 9 agent skills (#70-#77, #88) for D.intelligence business operations:
brand guardian, brand editor, doc secretary, quotation manager, service
architect, marketing manager, back office manager, account manager, and
skill update meta-agent. Includes shared Python package (dintel), reference
docs, document/quotation templates, service module CSVs, cross-device
installer, and comprehensive user guide.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom-skills/dintel-shared/pyproject.toml

@@ -0,0 +1,33 @@
+[project]
+name = "dintel"
+version = "0.1.0"
+description = "D.intelligence Agent Corps — shared Python utilities"
+requires-python = ">=3.12"
+license = "MIT"
+authors = [
+    { name = "Andrew Yim", email = "andrew.yim@dintelligence.co.kr" },
+]
+dependencies = [
+    "python-docx>=1.1.0",
+    "python-pptx>=0.6.23",
+    "openpyxl>=3.1.2",
+    "fpdf2>=2.7.9",
+    "Pillow>=10.3.0",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0",
+    "ruff>=0.4",
+]
+
+[build-system]
+requires = ["setuptools>=68.0", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools.packages.find]
+where = ["src"]
+
+[tool.ruff]
+line-length = 100
+target-version = "py312"