feat: Add OurDigital custom skills package (10 skills)

Complete implementation of OurDigital skills with dual-platform support
(Claude Desktop + Claude Code) following standardized structure.

Skills created:
- 01-ourdigital-brand-guide: Brand reference & style guidelines
- 02-ourdigital-blog: Korean blog drafts (blog.ourdigital.org)
- 03-ourdigital-journal: English essays (journal.ourdigital.org)
- 04-ourdigital-research: Research prompts & workflows
- 05-ourdigital-document: Notion-to-presentation pipeline
- 06-ourdigital-designer: Visual/image prompt generation
- 07-ourdigital-ad-manager: Ad copywriting & keyword research
- 08-ourdigital-trainer: Training materials & workshop planning
- 09-ourdigital-backoffice: Quotes, proposals, cost analysis
- 10-ourdigital-skill-creator: Meta skill for creating new skills

Features:
- YAML frontmatter with "ourdigital" or "our" prefix triggers
- Standardized directory structure (code/, desktop/, shared/, docs/)
- Shared environment setup (_ourdigital-shared/)
- Comprehensive reference documentation
- Cross-skill integration support

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

custom-skills/03-ourdigital-journal/shared/templates/essay-template.md

@@ -0,0 +1,64 @@
+---
+title: "{Evocative Title}"
+meta_description: "{Compelling 155-character description}"
+slug: "{url-slug}"
+tags: ["{tag1}", "{tag2}", "{tag3}"]
+author: "Andrew Yim"
+date: "{YYYY-MM-DD}"
+---
+
+# {Title}
+
+{Opening: Begin with a specific moment, scene, or question. Draw the reader into an experience before broadening to larger themes. This should feel intimate and immediate.}
+
+{Transition: Move from the specific to the general, hinting at the essay's territory.}
+
+---
+
+{First thread of exploration. Introduce an observation or idea that sets the stage for deeper inquiry. Weave in historical context or cultural reference.}
+
+{Develop the observation. Ask a rhetorical question that deepens the inquiry.}
+
+> {Pull quote or key insight that captures this section's essence.}
+
+{Connection to next thread—ideas should flow naturally.}
+
+---
+
+{Second thread. Build on the previous section, introducing a new angle or paradox. The complexity grows.}
+
+{Personal reflection or specific example that grounds abstract ideas.}
+
+{Analysis of what this means in broader context.}
+
+---
+
+{Third thread. Synthesis begins here. Threads start weaving together. New understanding emerges from the collision of ideas.}
+
+{Acknowledge tensions without resolving them. Epistemic humility—what we don't and can't know.}
+
+---
+
+## {Optional section heading for longer pieces}
+
+{Continue exploration if needed. Each section should add depth, not just length.}
+
+---
+
+{Closing: Return to something from the opening, but transformed by the journey. Leave an open question—not as evasion, but as invitation. The reader should leave thinking, not satisfied.}
+
+{Final rhetorical question or paradox that resonates.}
+
+---
+
+*Originally published in [OurDigital Journal](https://journal.ourdigital.org)*
+
+<!--
+Quality Checklist:
+- [ ] Evocative opening
+- [ ] Rhetorical questions throughout
+- [ ] Technical + human connection
+- [ ] At least one paradox
+- [ ] Open-ended closing
+- [ ] 1,000-2,000 words
+-->