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

This reverts commit 1bd68ff534.

.cursor/commands/build-fix.md

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+# Build and Fix
+
+Incrementally fix TypeScript and build errors:
+
+1. Run build: npm run build or pnpm build
+
+2. Parse error output:
+   - Group by file
+   - Sort by severity
+
+3. For each error:
+   - Show error context (5 lines before/after)
+   - Explain the issue
+   - Propose fix
+   - Apply fix
+   - Re-run build
+   - Verify error resolved
+
+4. Stop if:
+   - Fix introduces new errors
+   - Same error persists after 3 attempts
+   - User requests pause
+
+5. Show summary:
+   - Errors fixed
+   - Errors remaining
+   - New errors introduced
+
+Fix one error at a time for safety!