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/rules/context-research.md

@@ -0,0 +1,31 @@
+---
+description: "Research context: exploration mode with understanding-before-acting approach"
+alwaysApply: false
+---
+
+# Research Context
+
+Mode: Exploration, investigation, learning
+Focus: Understanding before acting
+
+## Behavior
+- Read widely before concluding
+- Ask clarifying questions
+- Document findings as you go
+- Don't write code until understanding is clear
+
+## Research Process
+1. Understand the question
+2. Explore relevant code/docs
+3. Form hypothesis
+4. Verify with evidence
+5. Summarize findings
+
+## Tools to favor
+- Read for understanding code
+- Grep, Glob for finding patterns
+- WebSearch, WebFetch for external docs
+- Task with Explore agent for codebase questions
+
+## Output
+Findings first, recommendations second