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/skills/strategic-compact/SKILL.md

@@ -0,0 +1,63 @@
+---
+name: strategic-compact
+description: Suggests manual context compaction at logical intervals to preserve context through task phases rather than arbitrary auto-compaction.
+---
+
+# Strategic Compact Skill
+
+Suggests manual `/compact` at strategic points in your workflow rather than relying on arbitrary auto-compaction.
+
+## Why Strategic Compaction?
+
+Auto-compaction triggers at arbitrary points:
+- Often mid-task, losing important context
+- No awareness of logical task boundaries
+- Can interrupt complex multi-step operations
+
+Strategic compaction at logical boundaries:
+- **After exploration, before execution** - Compact research context, keep implementation plan
+- **After completing a milestone** - Fresh start for next phase
+- **Before major context shifts** - Clear exploration context before different task
+
+## How It Works
+
+The `suggest-compact.sh` script runs on PreToolUse (Edit/Write) and:
+
+1. **Tracks tool calls** - Counts tool invocations in session
+2. **Threshold detection** - Suggests at configurable threshold (default: 50 calls)
+3. **Periodic reminders** - Reminds every 25 calls after threshold
+
+## Hook Setup
+
+Add to your `~/.claude/settings.json`:
+
+```json
+{
+  "hooks": {
+    "PreToolUse": [{
+      "matcher": "tool == \"Edit\" || tool == \"Write\"",
+      "hooks": [{
+        "type": "command",
+        "command": "~/.claude/skills/strategic-compact/suggest-compact.sh"
+      }]
+    }]
+  }
+}
+```
+
+## Configuration
+
+Environment variables:
+- `COMPACT_THRESHOLD` - Tool calls before first suggestion (default: 50)
+
+## Best Practices
+
+1. **Compact after planning** - Once plan is finalized, compact to start fresh
+2. **Compact after debugging** - Clear error-resolution context before continuing
+3. **Don't compact mid-implementation** - Preserve context for related changes
+4. **Read the suggestion** - The hook tells you *when*, you decide *if*
+
+## Related
+
+- [The Longform Guide](https://x.com/affaanmustafa/status/2014040193557471352) - Token optimization section
+- Memory persistence hooks - For state that survives compaction