feat(ecc): prune plugin 43→12 items, promote 7 rules to .claude/rules/ (#245)

ECC community plugin pruning: removed 530+ non-essential files
(.cursor/, .opencode/, docs/ja-JP, docs/zh-CN, docs/zh-TW,
language-specific skills/agents/rules). Retained 4 agents,
3 commands, 5 skills. Promoted 13 rule files (8 common + 5
typescript) to .claude/rules/ for CC native loading. Extracted
reusable patterns to EXTRACTED-PATTERNS.md.

.cursor/skills/continuous-learning/config.json

@@ -1,18 +0,0 @@
-{
-  "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"
-  ]
-}