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/refactor-clean.md

@@ -0,0 +1,28 @@
+# Refactor Clean
+
+Safely identify and remove dead code with test verification:
+
+1. Run dead code analysis tools:
+   - knip: Find unused exports and files
+   - depcheck: Find unused dependencies
+   - ts-prune: Find unused TypeScript exports
+
+2. Generate comprehensive report in .reports/dead-code-analysis.md
+
+3. Categorize findings by severity:
+   - SAFE: Test files, unused utilities
+   - CAUTION: API routes, components
+   - DANGER: Config files, main entry points
+
+4. Propose safe deletions only
+
+5. Before each deletion:
+   - Run full test suite
+   - Verify tests pass
+   - Apply change
+   - Re-run tests
+   - Rollback if tests fail
+
+6. Show summary of cleaned items
+
+Never delete code without running tests first!