fix(calendar): PDF programări via HTTP route, not Livewire wire:click

wire:click="exportPdf" attempted to return a binary Response through
Livewire's JSON channel — it re-encoded the PDF bytes as JSON and
triggered "Malformed UTF-8 characters, possibly incorrectly encoded".

Added GET /app/appointments/pdf?from=...&to=... that streams the PDF
with Content-Disposition: inline (or attachment when ?download=1) and
switched the calendar button to a plain <a target="_blank"> pointing
at that URL. The button now includes the currently visible period via
query params.

The old exportPdf() method is retained (still returns a plain PDF
Response) because CalendarEnhancementsTest asserts against it — it's
just no longer wired to the UI.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

resources/views/filament/tenant/pages/calendar.blade.php

@@ -159,7 +159,13 @@
             <h1>{{ __('Calendar vizual') }}</h1>
         </div>
         <div class="cv-btn-group">
-            <button class="cv-btn" wire:click="exportPdf">{{ __('🖨 PDF programări') }}</button>
+            @php
+                $_days = $this->getDays();
+                $_from = $_days[0]['date'] ?? today()->toDateString();
+                $_to = end($_days)['date'] ?? today()->toDateString();
+                $_pdfUrl = url('/app/appointments/pdf?from=' . $_from . '&to=' . $_to);
+            @endphp
+            <a class="cv-btn" href="{{ $_pdfUrl }}" target="_blank">{{ __('🖨 PDF programări') }}</a>
             <button class="cv-btn" wire:click="openNewPostForm">{{ __('+ Pod nou') }}</button>
             <button class="cv-btn cv-btn-primary" wire:click="openNewForm">{{ __('+ Programare nouă') }}</button>
         </div>