feat: Add mobile task index with 11ty build-time data

Phase 2 of task management consolidation:

- Added _data/tasks.js - fetches tasks from Gitea API at build time
- Added tasks-index.njk - mobile-friendly task list page
- Added node-fetch dependency for API calls
- Added .gitignore for node_modules and _site

Features:
- Shows only open/blocked tasks (filters out complete)
- Priority filtering (P1/P2/P3/P4)
- Color-coded priority badges (Fire/Gold/Frost/Arcane)
- Links to Gitea for full task details
- Mobile-optimized touch targets

Access at: firefrostgaming.com/tasks-index.html

Chronicler #69

.gitignore

@@ -0,0 +1,9 @@
+# Dependencies
+node_modules/
+
+# Build output (Cloudflare Pages builds this)
+_site/
+
+# Environment
+.env
+.env.local