Use consistent bash5 style for conditionals and quoting

AGENTS.md

@@ -1,7 +1,11 @@
 # Style
 
 - Two spaces for indentation, no tabs
-- Use bash 5 syntax: `[[ ]]` for conditionals, not `[ ]`. Don't quote variables inside `[[ ]]` (e.g., `[[ -n $var ]]` not `[[ -n "$var" ]]`)
+- Use bash 5 conditionals: use `[[ ]]` for string/file tests and `(( ))` for numeric tests
+- In `[[ ]]`, don't quote variables, but do quote string literals when comparing values (e.g., `[[ $branch == "dev" ]]`)
+- Prefer `(( ))` over numeric operators inside `[[ ]]` (e.g., `(( count < 50 ))`, not `[[ $count -lt 50 ]]`)
+- For strings/paths with spaces, quote them instead of escaping spaces with `\ ` (e.g., `"$APP_DIR/Disk Usage.desktop"`, not `$APP_DIR/Disk\ Usage.desktop`)
+- Shebangs must use `#!/bin/bash` consistently (never `#!/usr/bin/env bash`)
 
 # Command Naming