feat: implement stop alias management for Telegram import

- Added TelegramStopAliasService for handling stop aliases in the database.
- Created API endpoints for managing stop aliases (list, create, update, delete).
- Introduced TelegramStopAliases component in the frontend for user interaction with stop aliases.
- Updated TelegramImportService to utilize stop aliases for message processing.
- Enhanced telegramCancellationParser to resolve stop names using aliases.
- Added migration script to create telegram_stop_aliases table and seed initial data.
- Updated documentation to include details about stop alias functionality.

backend/migrations/014_telegram_stop_aliases.sql

@@ -0,0 +1,26 @@
+CREATE TABLE IF NOT EXISTS telegram_stop_aliases (
+  id SERIAL PRIMARY KEY,
+  city_id INTEGER NOT NULL REFERENCES cities(id) ON DELETE CASCADE,
+  alias VARCHAR(200) NOT NULL,
+  normalized_alias VARCHAR(200) NOT NULL CHECK (length(normalized_alias) > 0),
+  stop_id INTEGER NOT NULL REFERENCES stops(id) ON DELETE CASCADE,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  UNIQUE (city_id, normalized_alias)
+);
+
+-- Known carrier abbreviations are seeded only when the Polotsk stop is unique.
+-- Ambiguous platforms must be selected explicitly by an administrator.
+WITH defaults(alias, normalized_alias, stop_name) AS (
+  VALUES ('АВ/ВОКЗАЛ', 'аввокзал', 'Автовокзал'),
+         ('ЗОДЧЕГО', 'зодчего', 'Зодчего Иоанна')
+), candidates AS (
+  SELECT c.id AS city_id, d.alias, d.normalized_alias, min(s.id) AS stop_id
+  FROM defaults d JOIN cities c ON c.slug = 'polotsk'
+  JOIN stops s ON s.city_id = c.id AND s.is_active = true
+    AND lower(trim(s.name)) = lower(d.stop_name)
+  GROUP BY c.id, d.alias, d.normalized_alias HAVING count(*) = 1
+)
+INSERT INTO telegram_stop_aliases(city_id, alias, normalized_alias, stop_id)
+SELECT city_id, alias, normalized_alias, stop_id FROM candidates
+ON CONFLICT (city_id, normalized_alias) DO NOTHING;