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/88-dintel-skill-update/shared/change-log.md

@@ -0,0 +1,32 @@
+# D.intelligence Agent Corps — Change Log
+
+> Changes to shared references propagated across dintel- skills by Agent #88.
+
+---
+
+## Format
+
+```yaml
+- date: YYYY-MM-DD
+  type: pricing | brand-guide | service-module | notion-schema | client-code | terminology
+  description: "Brief description of change"
+  source_files:
+    - dintel-shared/src/dintel/brand.py
+  affected_skills:
+    - "#73 — updated pricing table"
+    - "#74 — updated module decision tree"
+  approved_by: Andrew
+```
+
+---
+
+## Log
+
+- date: 2026-03-08
+  type: initial-setup
+  description: "D.intelligence Agent Corps created — 8 agents (#70-#77) + meta-agent (#88)"
+  source_files:
+    - dintel-shared/ (all files)
+  affected_skills:
+    - "All skills — initial creation"
+  approved_by: Andrew