Migrate from Claude Code to OpenCode structure

- Move legacy content to legacy/ folder (old, old2, docs, learnings, scripts)
- Create new .opencode/ structure with skills/, tools/, agents/ folders
- Update Makefile to symlink to ~/.config/opencode/ instead of ~/.claude/
- Update Makefile to manage skills, tools, and agents (remove settings.json)
- Simplify install/uninstall (no backup logic)
- Add README.md documenting the new structure
- Keep settings.json as historical reference

legacy/old2/skills/dashboard/SKILL.md

@@ -0,0 +1,47 @@
+---
+name: dashboard
+description: >
+  Display milestones with unblocked issues at a glance.
+  Use when you want to see project progress and which issues are ready to work on.
+  Invoke with /dashboard [milestone-name-filter]
+model: claude-haiku-4-5
+user-invocable: true
+context: fork
+allowed-tools:
+  - Bash(~/.claude/skills/dashboard/scripts/generate-dashboard.sh*)
+---
+
+# Dashboard
+
+@~/.claude/skills/gitea/SKILL.md
+
+Display all milestones and their unblocked issues. Issues are considered unblocked if they have no open blockers in their dependency list.
+
+## Workflow
+
+1. **Run the dashboard script** with the milestone filter argument (if provided):
+   ```bash
+   ~/.claude/skills/dashboard/scripts/generate-dashboard.sh "$1"
+   ```
+
+2. **Display the output** to the user
+
+The script automatically:
+- Fetches all milestones from the repository
+- For each milestone, gets all open issues
+- For each issue, checks dependencies with `tea issues deps list`
+- Categorizes issues as unblocked (no open dependencies) or blocked (has open dependencies)
+- Displays results grouped by milestone in this format:
+
+```
+## Milestone: Release 1.0
+
+✓ Unblocked (3):
+  #42 Implement feature X
+  #43 Fix bug in Y
+  #45 Add tests for Z
+
+⊘ Blocked (2):
+  #40 Feature A (blocked by #39)
+  #41 Feature B (blocked by #38, #37)
+```