feat: Add A-Z filter for clients/suppliers in Telegram bot

- Add A-Z alphabetical filter keyboard for clients and suppliers lists
  (same pattern as company selection, without emoji)
- Increase clients/suppliers list pagination from 10 to 20 items per page
- Remove emoji from company A-Z filter button for consistency
- Add 6 new callback handlers: clients_alpha_menu, clients_alpha:LETTER,
  clients_alpha_page:PAGE:LETTER, and supplier equivalents
- Dashboard service and models updates
- Telegram bot: email handlers, auth, DB operations, internal API improvements
- Frontend: dashboard cards updates (CashFlow, Clienti, Furnizori, Treasury)
- Frontend: SolduriCompactCard and CollapsibleCard improvements
- DashboardView enhancements
- start.sh and run-with-restart.sh script updates
- IIS web.config and service worker updates

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/modules/telegram/bot/helpers.py

@@ -169,7 +169,10 @@ def create_company_selection_keyboard(
 def create_company_selection_keyboard_paginated(
     companies: List[Dict[str, Any]],
     page: int = 0,
-    per_page: int = 10
+    per_page: int = 20,
+    back_callback: str = "action:menu",
+    page_callback_prefix: str = "select_company_page",
+    page_callback_suffix: str = ""
 ) -> InlineKeyboardMarkup:
     """
     Create paginated inline keyboard for company selection.
@@ -180,7 +183,10 @@ def create_company_selection_keyboard_paginated(
     Args:
         companies: Full list of company dicts (with id, nume_firma, cui)
         page: Current page number (0-indexed)
-        per_page: Number of companies per page (default: 10)
+        per_page: Number of companies per page (default: 20)
+        back_callback: Callback data for the back button (default: "action:menu")
+        page_callback_prefix: Prefix for pagination callbacks (default: "select_company_page")
+        page_callback_suffix: Suffix appended after page number in pagination callbacks
 
     Returns:
         InlineKeyboardMarkup with company buttons and pagination controls
@@ -221,8 +227,9 @@ def create_company_selection_keyboard_paginated(
 
         # Previous button
         if page > 0:
+            prev_cb = f"{page_callback_prefix}:{page-1}{page_callback_suffix}"
             nav_buttons.append(
-                InlineKeyboardButton("< Anterior", callback_data=f"select_company_page:{page-1}")
+                InlineKeyboardButton("< Anterior", callback_data=prev_cb)
             )
 
         # Page indicator (non-clickable)
@@ -232,20 +239,76 @@ def create_company_selection_keyboard_paginated(
 
         # Next button
         if page < total_pages - 1:
+            next_cb = f"{page_callback_prefix}:{page+1}{page_callback_suffix}"
             nav_buttons.append(
-                InlineKeyboardButton("Urmator >", callback_data=f"select_company_page:{page+1}")
+                InlineKeyboardButton("Urmator >", callback_data=next_cb)
             )
 
         keyboard.append(nav_buttons)
 
-    # Back to menu button
+    # A-Z filter + back button
     keyboard.append([
-        InlineKeyboardButton("< Inapoi la Meniu", callback_data="action:menu")
+        InlineKeyboardButton("Filtrare A-Z", callback_data="select_company_alpha_menu")
+    ])
+    keyboard.append([
+        InlineKeyboardButton("« Înapoi", callback_data=back_callback)
     ])
 
     return InlineKeyboardMarkup(keyboard)
 
 
+def create_alpha_filter_keyboard() -> InlineKeyboardMarkup:
+    """
+    Create inline keyboard with A–Z letter buttons for filtering companies.
+
+    Displays 26 letter buttons in rows of 6, plus a 'Toată lista' button
+    that shows all companies without filtering.
+
+    Returns:
+        InlineKeyboardMarkup with letter buttons and navigation
+    """
+    letters = list("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+    keyboard = []
+    row_size = 6
+    for i in range(0, len(letters), row_size):
+        row = [
+            InlineKeyboardButton(l, callback_data=f"select_company_alpha:{l}")
+            for l in letters[i:i + row_size]
+        ]
+        keyboard.append(row)
+    keyboard.append([
+        InlineKeyboardButton("Toată lista", callback_data="select_company_alpha:ALL"),
+        InlineKeyboardButton("« Meniu", callback_data="action:menu")
+    ])
+    return InlineKeyboardMarkup(keyboard)
+
+
+def create_alpha_filter_keyboard_partner(partner_type: str) -> InlineKeyboardMarkup:
+    """
+    Create inline keyboard with A–Z letter buttons for filtering clients or suppliers.
+
+    Args:
+        partner_type: "clients" or "suppliers"
+
+    Returns:
+        InlineKeyboardMarkup with letter buttons and navigation
+    """
+    letters = list("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+    keyboard = []
+    row_size = 6
+    for i in range(0, len(letters), row_size):
+        row = [
+            InlineKeyboardButton(l, callback_data=f"{partner_type}_alpha:{l}")
+            for l in letters[i:i + row_size]
+        ]
+        keyboard.append(row)
+    keyboard.append([
+        InlineKeyboardButton("Toata lista", callback_data=f"{partner_type}_alpha:ALL"),
+        InlineKeyboardButton("« Meniu", callback_data="action:menu")
+    ])
+    return InlineKeyboardMarkup(keyboard)
+
+
 def format_company_context_footer(company_name: str) -> str:
     """
     Format discrete footer with company context.