chore: add multi-agent editor config and UBS file-write hook

Add rule/config files for Cursor, Cline, Codex, Gemini, Continue, and
OpenCode editors pointing them to project conventions, UBS usage, and
AGENTS.md. Add a Claude Code on-file-write hook that runs UBS on
supported source files after every save.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/hooks/on-file-write.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+# Ultimate Bug Scanner - Claude Code Hook
+# Runs on every file save for UBS-supported languages (JS/TS, Python, C/C++, Rust, Go, Java, Ruby)
+
+if [[ "$FILE_PATH" =~ \.(js|jsx|ts|tsx|mjs|cjs|py|pyw|pyi|c|cc|cpp|cxx|h|hh|hpp|hxx|rs|go|java|rb)$ ]]; then
+  echo "🔬 Running bug scanner..."
+  if ! command -v ubs >/dev/null 2>&1; then
+    echo "⚠️  'ubs' not found in PATH; install it before using this hook." >&2
+    exit 0
+  fi
+  ubs "${PROJECT_DIR}" --ci 2>&1 | head -50
+fi