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.

commands/build-fix.md

@@ -1,62 +0,0 @@
-# Build and Fix
-
-Incrementally fix build and type errors with minimal, safe changes.
-
-## Step 1: Detect Build System
-
-Identify the project's build tool and run the build:
-
-| Indicator | Build Command |
-|-----------|---------------|
-| `package.json` with `build` script | `npm run build` or `pnpm build` |
-| `tsconfig.json` (TypeScript only) | `npx tsc --noEmit` |
-| `Cargo.toml` | `cargo build 2>&1` |
-| `pom.xml` | `mvn compile` |
-| `build.gradle` | `./gradlew compileJava` |
-| `go.mod` | `go build ./...` |
-| `pyproject.toml` | `python -m py_compile` or `mypy .` |
-
-## Step 2: Parse and Group Errors
-
-1. Run the build command and capture stderr
-2. Group errors by file path
-3. Sort by dependency order (fix imports/types before logic errors)
-4. Count total errors for progress tracking
-
-## Step 3: Fix Loop (One Error at a Time)
-
-For each error:
-
-1. **Read the file** — Use Read tool to see error context (10 lines around the error)
-2. **Diagnose** — Identify root cause (missing import, wrong type, syntax error)
-3. **Fix minimally** — Use Edit tool for the smallest change that resolves the error
-4. **Re-run build** — Verify the error is gone and no new errors introduced
-5. **Move to next** — Continue with remaining errors
-
-## Step 4: Guardrails
-
-Stop and ask the user if:
-- A fix introduces **more errors than it resolves**
-- The **same error persists after 3 attempts** (likely a deeper issue)
-- The fix requires **architectural changes** (not just a build fix)
-- Build errors stem from **missing dependencies** (need `npm install`, `cargo add`, etc.)
-
-## Step 5: Summary
-
-Show results:
-- Errors fixed (with file paths)
-- Errors remaining (if any)
-- New errors introduced (should be zero)
-- Suggested next steps for unresolved issues
-
-## Recovery Strategies
-
-| Situation | Action |
-|-----------|--------|
-| Missing module/import | Check if package is installed; suggest install command |
-| Type mismatch | Read both type definitions; fix the narrower type |
-| Circular dependency | Identify cycle with import graph; suggest extraction |
-| Version conflict | Check `package.json` / `Cargo.toml` for version constraints |
-| Build tool misconfiguration | Read config file; compare with working defaults |
-
-Fix one error at a time for safety. Prefer minimal diffs over refactoring.