feat(cli): add beautiful colored output and fix daemon exit bug

Major improvements:
- Created color theme system (ts/colors.ts) with ANSI colors
- Enhanced logger with colors, table formatting, and styled boxes
- Fixed daemon exit bug - now stays running when no UPS configured
- Added config hot-reload with file watcher for live updates
- Beautified CLI help output with color-coded commands
- Added showcase test demonstrating all output features
- Fixed ANSI code handling for perfect table/box alignment

Features:
- Color-coded messages (success=green, error=red, warning=yellow, info=cyan)
- Status symbols (●○◐◯ for running/stopped/starting/unknown)
- Battery level colors (green>60%, yellow 30-60%, red<30%)
- Table formatting with auto-sizing and column alignment
- Styled boxes (success, error, warning, info styles)
- Hot-reload: daemon watches config file and reloads automatically
- Idle mode: daemon stays alive when no devices, checks periodically

Daemon improvements:
- No longer exits when no UPS devices configured
- Enters idle monitoring loop waiting for config
- File watcher detects config changes in real-time
- Auto-reloads and starts monitoring when devices added
- Logs warnings instead of errors for missing devices

Technical fixes:
- Strip ANSI codes when calculating text width for alignment
- Use visible length for padding calculations in tables and boxes
- Properly handle colored text in table cells and box lines

Breaking changes: None (backward compatible)

ts/colors.ts

@@ -0,0 +1,89 @@
+/**
+ * Color theme and styling utilities for NUPST CLI
+ * Uses Deno standard library colors module
+ */
+import * as colors from '@std/fmt/colors';
+
+/**
+ * Color theme for consistent CLI styling
+ */
+export const theme = {
+  // Message types
+  error: colors.red,
+  warning: colors.yellow,
+  success: colors.green,
+  info: colors.cyan,
+  dim: colors.dim,
+  highlight: colors.bold,
+  bright: colors.bright,
+
+  // Status indicators
+  statusActive: (text: string) => colors.green(colors.bold(text)),
+  statusInactive: (text: string) => colors.red(text),
+  statusWarning: (text: string) => colors.yellow(text),
+  statusUnknown: (text: string) => colors.dim(text),
+
+  // Battery level colors
+  batteryGood: colors.green, // > 60%
+  batteryMedium: colors.yellow, // 30-60%
+  batteryCritical: colors.red, // < 30%
+
+  // Box borders
+  borderSuccess: colors.green,
+  borderError: colors.red,
+  borderWarning: colors.yellow,
+  borderInfo: colors.cyan,
+  borderDefault: (text: string) => text, // No color
+
+  // Command/code highlighting
+  command: colors.cyan,
+  code: colors.dim,
+  path: colors.blue,
+};
+
+/**
+ * Status symbols with colors
+ */
+export const symbols = {
+  success: colors.green('✓'),
+  error: colors.red('✗'),
+  warning: colors.yellow('⚠'),
+  info: colors.cyan('ℹ'),
+  running: colors.green('●'),
+  stopped: colors.red('○'),
+  starting: colors.yellow('◐'),
+  unknown: colors.dim('◯'),
+};
+
+/**
+ * Get color for battery level
+ */
+export function getBatteryColor(percentage: number): (text: string) => string {
+  if (percentage >= 60) return theme.batteryGood;
+  if (percentage >= 30) return theme.batteryMedium;
+  return theme.batteryCritical;
+}
+
+/**
+ * Get color for runtime remaining
+ */
+export function getRuntimeColor(minutes: number): (text: string) => string {
+  if (minutes >= 20) return theme.batteryGood;
+  if (minutes >= 10) return theme.batteryMedium;
+  return theme.batteryCritical;
+}
+
+/**
+ * Format UPS power status with color
+ */
+export function formatPowerStatus(status: 'online' | 'onBattery' | 'unknown'): string {
+  switch (status) {
+    case 'online':
+      return theme.success('Online');
+    case 'onBattery':
+      return theme.warning('On Battery');
+    case 'unknown':
+    default:
+      return theme.dim('Unknown');
+  }
+}