chore: update dependencies

Backend:
- gunicorn 23.0.0 → 25.1.0
- setuptools 79.0.1 → 82.0.1
- litellm >=1.72.3 → >=1.82.1

Frontend:
- Migrate Tailwind CSS 3 → 4, daisyUI 4 → 5
  - Add @tailwindcss/vite plugin, remove autoprefixer
  - Replace tailwind.config.js with src/app.css (CSS-based config)
  - Convert custom themes (aestheticDark, catppuccinMocha, aestheticLight,
    northernLights) to daisyUI 5 CSS variable format
  - Remove daisyUI v4-only '-bordered' classes from 45 component files
    (input-bordered, select-bordered, textarea-bordered, file-input-bordered
    are removed in v5; borders are default)
- @types/node 22 → 25
- @lukulent/svelte-umami 0.0.3 → 0.0.4
- packageManager: bun@1.2.22 → bun@1.3.10

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/lib/components/AITravelChat.svelte

@@ -823,7 +823,7 @@
 									</label>
 									<select
 										id="chat-provider-select"
-										class="select select-bordered select-sm w-full"
+										class="select select-sm w-full"
 										bind:value={selectedProvider}
 										disabled={chatProviders.length === 0}
 									>
@@ -840,7 +840,7 @@
 									</label>
 									<select
 										id="chat-model-select"
-										class="select select-bordered select-sm w-full"
+										class="select select-sm w-full"
 										bind:value={selectedModel}
 										disabled={chatProviders.length === 0}
 									>
@@ -1020,7 +1020,7 @@
 						</div>
 						<div class="flex items-end gap-2" class:mx-auto={!embedded} class:max-w-4xl={!embedded}>
 							<textarea
-								class="textarea textarea-bordered flex-1 resize-none"
+								class="textarea flex-1 resize-none"
 								placeholder={$t('chat.input_placeholder')}
 								bind:value={inputMessage}
 								on:keydown={handleKeydown}
@@ -1059,7 +1059,7 @@
 
 			<input
 				type="date"
-				class="input input-bordered w-full"
+				class="input w-full"
 				bind:value={selectedDate}
 				min={startDate}
 				max={endDate}