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/continuous-learning/config.json

@@ -0,0 +1,18 @@
+{
+  "min_session_length": 10,
+  "extraction_threshold": "medium",
+  "auto_approve": false,
+  "learned_skills_path": "~/.claude/skills/learned/",
+  "patterns_to_detect": [
+    "error_resolution",
+    "user_corrections",
+    "workarounds",
+    "debugging_techniques",
+    "project_specific"
+  ],
+  "ignore_patterns": [
+    "simple_typos",
+    "one_time_fixes",
+    "external_api_issues"
+  ]
+}