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/75-dintel-marketing-mgr/README.md

@@ -0,0 +1,69 @@
+# 75 — D.intelligence Marketing Manager
+
+**Agent #75** in the [D.intelligence Agent Corps](../../dintel-shared/README.md).
+Marketing content pipeline management for [D.intelligence](https://dintelligence.co.kr).
+
+## What It Does
+
+1. **Magazine D. Articles** — Draft blog posts for dintelligence.co.kr/dintelligence-magazine/
+2. **Newsletter Content** — Prepare newsletter editions with insights and key metrics
+3. **Social Media** — Draft LinkedIn posts and social content
+4. **WordPress Publishing** — Prepare content for WordPress CMS (dintelligence.co.kr)
+5. **Content Calendar** — Plan and track content publication schedule
+6. **SEO Integration** — Ensure content follows SEO best practices and strategic keywords
+
+## Agent Corps Context
+
+| Field | Value |
+|-------|-------|
+| Agent # | 75 |
+| Skill Name | `dintel-marketing-mgr` |
+| Version | 1.0.0 |
+| Autonomy | **Draft & Wait** — drafts content, waits for Andrew's approval before publishing |
+| Collaborates With | **#71 Brand Editor** (writing check), **#70 Brand Guardian** (compliance review), **dintel-shared** (shared constants) |
+
+This agent uses shared brand constants from `dintel-shared/src/dintel/brand.py` for colors, terminology, and style rules.
+
+## Content Pipeline (Chain C)
+
+```
+Marketing Mgr (#75) drafts
+  → Brand Editor (#71) checks writing
+    → Brand Guardian (#70) reviews compliance
+      → Andrew approves
+        → WordPress publish
+```
+
+## Triggers
+
+- "draft Magazine D. article", "Magazine D. 아티클 초안"
+- "prepare newsletter", "뉴스레터 준비"
+- "draft LinkedIn post", "LinkedIn 포스트 작성"
+- "content calendar", "콘텐츠 캘린더"
+- "plan marketing content", "마케팅 콘텐츠 기획"
+- "WordPress content", "워드프레스 콘텐츠"
+
+## Brand Reference
+
+Based on the [D.intelligence Brand Guide](https://www.notion.so/dintelligence/Review-D-intelligence-Brand-Guide-31c581e58a1e805eb980cf01ccc9a8d4) from Notion.
+
+## Universal Guardrails
+
+1. **Never send to clients without Andrew's approval** — All client-facing content must be reviewed and approved by Andrew before delivery.
+2. **Never delete — always archive** — Move outdated content to archive; never permanently delete.
+3. **Never commit pricing without Andrew's sign-off** — Pricing, quotes, and fee-related content require explicit approval.
+4. **Korean-first, bilingual notation for jargon** — Korean is the primary language; technical/English terms use 한글(English) bilingual notation on first use.
+5. **Never cross-reference client data without consent** — Client data is siloed; do not mix or reference across client accounts without explicit permission.
+
+## Structure
+
+```
+75-dintel-marketing-mgr/
+├── code/
+│   └── CLAUDE.md              # Claude Code directive
+├── desktop/
+│   └── SKILL.md               # Claude Desktop skill
+├── shared/
+│   └── content-calendar-template.md  # Content calendar template
+└── README.md
+```