feat: add Cursor IDE support with pre-translated configs

Add complete .cursor/ directory with rules, agents, skills, commands,
and MCP config adapted for Cursor's format. This makes ecc-universal
a truly cross-IDE package supporting Claude Code, Cursor, and OpenCode.

- 27 rule files with YAML frontmatter (description, globs, alwaysApply)
- 13 agent files with full model IDs and readonly flags
- 30 skill directories (identical Agent Skills standard, no translation)
- 31 command files (5 multi-* stubbed for missing codeagent-wrapper)
- MCP config with Cursor env interpolation syntax
- README.md and MIGRATION.md documentation
- install.sh --target cursor flag for project-scoped installation
- package.json updated with .cursor/ in files and cursor keywords

.cursor/commands/learn.md

@@ -0,0 +1,70 @@
+# /learn - Extract Reusable Patterns
+
+Analyze the current session and extract any patterns worth saving as skills.
+
+## Trigger
+
+Run `/learn` at any point during a session when you've solved a non-trivial problem.
+
+## What to Extract
+
+Look for:
+
+1. **Error Resolution Patterns**
+   - What error occurred?
+   - What was the root cause?
+   - What fixed it?
+   - Is this reusable for similar errors?
+
+2. **Debugging Techniques**
+   - Non-obvious debugging steps
+   - Tool combinations that worked
+   - Diagnostic patterns
+
+3. **Workarounds**
+   - Library quirks
+   - API limitations
+   - Version-specific fixes
+
+4. **Project-Specific Patterns**
+   - Codebase conventions discovered
+   - Architecture decisions made
+   - Integration patterns
+
+## Output Format
+
+Create a skill file at `skills/learned/[pattern-name].md`:
+
+```markdown
+# [Descriptive Pattern Name]
+
+**Extracted:** [Date]
+**Context:** [Brief description of when this applies]
+
+## Problem
+[What problem this solves - be specific]
+
+## Solution
+[The pattern/technique/workaround]
+
+## Example
+[Code example if applicable]
+
+## When to Use
+[Trigger conditions - what should activate this skill]
+```
+
+## Process
+
+1. Review the session for extractable patterns
+2. Identify the most valuable/reusable insight
+3. Draft the skill file
+4. Ask user to confirm before saving
+5. Save to `skills/learned/`
+
+## Notes
+
+- Don't extract trivial fixes (typos, simple syntax errors)
+- Don't extract one-time issues (specific API outages, etc.)
+- Focus on patterns that will save time in future sessions
+- Keep skills focused - one pattern per skill