Refactor frontend to Composition API and improve UI/UX

Major Changes:
- Migrate components from Options API to Composition API with <script setup>
- Add centralized service layer (serviceService, deliveryService, adminService)
- Implement new reusable components (EnhancedButton, EnhancedModal, StatCard, etc.)
- Add theme store for consistent theming across application
- Improve ServiceCalendar with federal holidays and better styling
- Refactor customer profile and tank estimation components
- Update all delivery and payment pages to use centralized services
- Add utility functions for formatting and validation
- Update Dockerfiles for better environment configuration
- Enhance Tailwind config with custom design tokens

UI Improvements:
- Modern, premium design with glassmorphism effects
- Improved form layouts with FloatingInput components
- Better loading states and empty states
- Enhanced modals and tables with consistent styling
- Responsive design improvements across all pages

Technical Improvements:
- Strict TypeScript types throughout
- Better error handling and validation
- Removed deprecated api.js in favor of TypeScript services
- Improved code organization and maintainability

src/stores/theme.ts

@@ -0,0 +1,52 @@
+// src/stores/theme.ts
+
+import { ref } from 'vue'
+import { defineStore } from 'pinia'
+import type { ThemeOption } from '../types/models'
+
+const STORAGE_KEY = 'user_theme'
+const DEFAULT_THEME = 'ocean'
+
+export const AVAILABLE_THEMES: ThemeOption[] = [
+  { name: 'ocean', label: 'Ocean', preview: '#ff6600' },
+  { name: 'forest', label: 'Forest', preview: '#4ade80' },
+  { name: 'sunset', label: 'Sunset', preview: '#fb923c' },
+  { name: 'arctic', label: 'Arctic', preview: '#06b6d4' },
+  { name: 'midnight', label: 'Midnight', preview: '#a78bfa' },
+]
+
+export const useThemeStore = defineStore('theme', () => {
+  // --- STATE ---
+  const currentTheme = ref(localStorage.getItem(STORAGE_KEY) || DEFAULT_THEME)
+
+  // --- ACTIONS ---
+  function setTheme(theme: string) {
+    const validTheme = AVAILABLE_THEMES.find(t => t.name === theme)
+    if (validTheme) {
+      currentTheme.value = theme
+      localStorage.setItem(STORAGE_KEY, theme)
+      document.documentElement.setAttribute('data-theme', theme)
+    }
+  }
+
+  function initTheme() {
+    // Validate stored theme is still valid
+    const storedTheme = localStorage.getItem(STORAGE_KEY)
+    const validTheme = AVAILABLE_THEMES.find(t => t.name === storedTheme)
+    if (validTheme) {
+      currentTheme.value = storedTheme!
+    } else {
+      currentTheme.value = DEFAULT_THEME
+      localStorage.setItem(STORAGE_KEY, DEFAULT_THEME)
+    }
+    document.documentElement.setAttribute('data-theme', currentTheme.value)
+  }
+
+  // --- RETURN ---
+  return {
+    currentTheme,
+    setTheme,
+    initTheme,
+    AVAILABLE_THEMES,
+  }
+})