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/mcp.json

@@ -0,0 +1,70 @@
+{
+  "mcpServers": {
+    "github": {
+      "command": "npx",
+      "args": ["-y", "@modelcontextprotocol/server-github"],
+      "env": {
+        "GITHUB_PERSONAL_ACCESS_TOKEN": "${env:GITHUB_PERSONAL_ACCESS_TOKEN}"
+      }
+    },
+    "firecrawl": {
+      "command": "npx",
+      "args": ["-y", "firecrawl-mcp"],
+      "env": {
+        "FIRECRAWL_API_KEY": "${env:FIRECRAWL_API_KEY}"
+      }
+    },
+    "supabase": {
+      "command": "npx",
+      "args": ["-y", "@supabase/mcp-server-supabase@latest", "--project-ref=YOUR_PROJECT_REF"]
+    },
+    "memory": {
+      "command": "npx",
+      "args": ["-y", "@modelcontextprotocol/server-memory"]
+    },
+    "sequential-thinking": {
+      "command": "npx",
+      "args": ["-y", "@modelcontextprotocol/server-sequential-thinking"]
+    },
+    "vercel": {
+      "type": "http",
+      "url": "https://mcp.vercel.com"
+    },
+    "railway": {
+      "command": "npx",
+      "args": ["-y", "@railway/mcp-server"]
+    },
+    "cloudflare-docs": {
+      "type": "http",
+      "url": "https://docs.mcp.cloudflare.com/mcp"
+    },
+    "cloudflare-workers-builds": {
+      "type": "http",
+      "url": "https://builds.mcp.cloudflare.com/mcp"
+    },
+    "cloudflare-workers-bindings": {
+      "type": "http",
+      "url": "https://bindings.mcp.cloudflare.com/mcp"
+    },
+    "cloudflare-observability": {
+      "type": "http",
+      "url": "https://observability.mcp.cloudflare.com/mcp"
+    },
+    "clickhouse": {
+      "type": "http",
+      "url": "https://mcp.clickhouse.cloud/mcp"
+    },
+    "context7": {
+      "command": "npx",
+      "args": ["-y", "@context7/mcp-server"]
+    },
+    "magic": {
+      "command": "npx",
+      "args": ["-y", "@magicuidesign/mcp@latest"]
+    },
+    "filesystem": {
+      "command": "npx",
+      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/your/projects"]
+    }
+  }
+}