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/76-dintel-backoffice-mgr/README.md

@@ -0,0 +1,59 @@
+# 76-dintel-backoffice-mgr
+
+> **Agent #76** | `dintel-backoffice-mgr` v1.0.0 | D.intelligence Agent Corps
+
+Back Office & HR Manager -- handles administrative operations, invoicing, contracts, HR tasks, expense tracking, and compliance for D.intelligence.
+
+## Autonomy Level
+
+**Draft & Wait** -- Drafts administrative documents (invoices, contracts, checklists), then waits for Andrew's review and approval before any external action.
+
+## Key Responsibilities
+
+| Area | Description |
+|------|-------------|
+| **Invoicing & Billing** | Generate invoices, track billing cycles, manage accounts receivable |
+| **Contract Management** | Draft service contracts (SOW), NDA templates, renewal notices |
+| **HR Operations** | Onboarding/offboarding checklists, part-time contractor management |
+| **Expense Tracking** | Monthly expense summaries, budget tracking |
+| **Compliance** | Tax document preparation reminders, regulatory compliance tracking |
+| **Office Administration** | Supplies, subscriptions, license renewals |
+
+## Team Context
+
+- **Andrew Yim**: Founder & sole full-time operator
+- **Office Manager**: Part-time contractor -- back office, accounting, some HR
+- **Ad Manager**: Support role -- advertising settings and client support
+- All other work: Andrew + AI Agent Corps
+
+## Directory Structure
+
+```
+76-dintel-backoffice-mgr/
+├── code/
+│   └── CLAUDE.md              # Claude Code instructions
+├── desktop/
+│   └── SKILL.md               # Full skill definition for Claude Desktop
+├── shared/
+│   └── billing-checklist.md   # Monthly billing checklist & procedures
+└── README.md                  # This file
+```
+
+## Key References
+
+- Document Templates: `/Users/ourdigital/Documents/D.intelligence Service Package/Source Files/문서 양식/`
+- Service Map: `/Users/ourdigital/Documents/D.intelligence Service Package/00_SERVICE-MAP.md`
+- Pricing Packages: `/Users/ourdigital/Documents/D.intelligence Service Package/06_PRICING-PACKAGES.md`
+- Shared Utilities: `../../dintel-shared/src/dintel/`
+
+## Workflow Chain
+
+**Chain D**: Back Office Mgr (#76) --> Doc Secretary (#72) formats
+
+## Universal Guardrails
+
+1. Never send to clients without Andrew's approval
+2. Never delete -- always archive
+3. Never commit pricing without Andrew's sign-off
+4. Korean-first, jargon = 한글(English) bilingual notation
+5. Never cross-reference client data without consent