chore: add platform identity and platform_messages for multi-platform support (#23)

TDD cycle for issue #23:
- RED: 9 migration smoke tests (file presence + schema expectations)
- GREEN: V016 migration adding platform identity columns
- GREEN: CreateSessionHandler, JoinSessionHandler, Web SessionService updated
  with dual-write to legacy and new identity columns + COALESCE fallbacks
- GREEN: get_group_attendance_stats recreated for external_username
- Bump version to 2.0.0

Changes:
- V016__add_platform_identity.sql:
  - players: platform, external_user_id, external_username
  - game_groups: platform, external_group_id, external_channel_id
  - platform_messages table with cross-platform message tracking
  - Backfill all existing Telegram data into new columns
  - Recreate get_group_attendance_stats with COALESCE fallback
- V012__add_attendance_stats.sql: use COALESCE(external_username, telegram_username)
- CreateSessionHandler: dual-write + COALESCE fallbacks in SELECTs
- JoinSessionHandler: dual-write to new identity columns
- Web SessionService: dual-write to new identity columns
- PlatformIdentityMigrationTests (9 smoke tests covering all handlers)
- Version synced: Directory.Build.props, compose.yaml, deploy.yml, NavMenu.razor → 2.0.0

Legacy telegram_* columns preserved for backward compatibility.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/GmRelay.Bot/Features/Sessions/CreateSession/JoinSessionHandler.cs

@@ -35,9 +35,14 @@ public sealed class JoinSessionHandler(
         {
             // 1. Убеждаемся, что игрок есть в базе
             var playerId = await connection.ExecuteScalarAsync<Guid>(
-                @"INSERT INTO players (telegram_id, display_name, telegram_username) 
-                  VALUES (@TgId, @Name, @Username)
-                  ON CONFLICT (telegram_id) DO UPDATE SET display_name = EXCLUDED.display_name, telegram_username = EXCLUDED.telegram_username
+                @"INSERT INTO players (telegram_id, display_name, telegram_username, platform, external_user_id, external_username)
+                  VALUES (@TgId, @Name, @Username, 'Telegram', @TgId::TEXT, @Username)
+                  ON CONFLICT (telegram_id) DO UPDATE
+                  SET display_name = EXCLUDED.display_name,
+                      telegram_username = EXCLUDED.telegram_username,
+                      platform = COALESCE(players.platform, 'Telegram'),
+                      external_user_id = COALESCE(players.external_user_id, EXCLUDED.telegram_id::TEXT),
+                      external_username = COALESCE(players.external_username, EXCLUDED.telegram_username)
                   RETURNING id;",
                 new { TgId = command.TelegramUserId, Name = command.DisplayName, Username = command.TelegramUsername },
                 transaction);

src/GmRelay.Bot/Migrations/V016__add_platform_identity.sql

@@ -5,7 +5,7 @@
 -- Legacy telegram_* columns are retained for backward compatibility.
 -- =============================================================
 
--- ── Players: platform-agnostic identity ─────────────────────────
+-- -- Players: platform-agnostic identity
 ALTER TABLE players
     ADD COLUMN platform          VARCHAR(50),
     ADD COLUMN external_user_id  VARCHAR(255),
@@ -15,7 +15,7 @@ CREATE UNIQUE INDEX ix_players_platform_external_user_id
     ON players (platform, external_user_id)
     WHERE platform IS NOT NULL AND external_user_id IS NOT NULL;
 
--- ── Game groups: platform-agnostic identity ─────────────────────
+-- -- Game groups: platform-agnostic identity
 ALTER TABLE game_groups
     ADD COLUMN platform           VARCHAR(50),
     ADD COLUMN external_group_id  VARCHAR(255),
@@ -25,7 +25,7 @@ CREATE UNIQUE INDEX ix_game_groups_platform_external_group_id
     ON game_groups (platform, external_group_id)
     WHERE platform IS NOT NULL AND external_group_id IS NOT NULL;
 
--- ── Backfill existing Telegram data ─────────────────────────────
+-- -- Backfill existing Telegram data
 UPDATE players
    SET platform          = 'Telegram',
        external_user_id  = telegram_id::TEXT,
@@ -37,7 +37,7 @@ UPDATE game_groups
        external_group_id = telegram_chat_id::TEXT
  WHERE platform IS NULL;
 
--- ── Platform messages: store per-platform message references ────
+-- -- Platform messages: store per-platform message references
 CREATE TABLE platform_messages (
     id                   UUID PRIMARY KEY DEFAULT gen_random_uuid(),
     platform             VARCHAR(50) NOT NULL,
@@ -57,7 +57,7 @@ CREATE INDEX ix_platform_messages_session_id   ON platform_messages(session_id);
 CREATE INDEX ix_platform_messages_platform_message
     ON platform_messages (platform, external_message_id);
 
--- ── Recreate attendance stats function for new columns (prod back-compat) ──
+-- -- Recreate attendance stats function for new columns (prod back-compat)
 CREATE OR REPLACE FUNCTION get_group_attendance_stats(p_group_id UUID)
 RETURNS TABLE (
     player_id           UUID,

src/GmRelay.Web/Services/SessionService.cs

@@ -242,11 +242,14 @@ public sealed class SessionService(
 
         await conn.ExecuteAsync(
             """
-            INSERT INTO players (telegram_id, display_name, telegram_username)
-            VALUES (@TelegramId, @DisplayName, @TelegramUsername)
+            INSERT INTO players (telegram_id, display_name, telegram_username, platform, external_user_id, external_username)
+            VALUES (@TelegramId, @DisplayName, @TelegramUsername, 'Telegram', @TelegramId::TEXT, @TelegramUsername)
             ON CONFLICT (telegram_id) DO UPDATE
             SET display_name = EXCLUDED.display_name,
-                telegram_username = EXCLUDED.telegram_username
+                telegram_username = EXCLUDED.telegram_username,
+                platform = COALESCE(players.platform, 'Telegram'),
+                external_user_id = COALESCE(players.external_user_id, EXCLUDED.telegram_id::TEXT),
+                external_username = COALESCE(players.external_username, EXCLUDED.telegram_username)
             """,
             new
             {

tests/GmRelay.Bot.Tests/Infrastructure/Database/PlatformIdentityMigrationTests.cs

@@ -71,6 +71,26 @@ public sealed class PlatformIdentityMigrationTests
         Assert.Contains("external_group_id", createHandler, StringComparison.Ordinal);
     }
 
+    [Fact]
+    public async Task JoinSessionHandler_ShouldDualWritePlatformIdentity()
+    {
+        var handler = await ReadRepositoryFileAsync("src/GmRelay.Bot/Features/Sessions/CreateSession/JoinSessionHandler.cs");
+
+        Assert.Contains("external_user_id", handler, StringComparison.Ordinal);
+        Assert.Contains("external_username", handler, StringComparison.Ordinal);
+        Assert.Contains("platform", handler, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public async Task WebSessionService_ShouldDualWritePlatformIdentity()
+    {
+        var service = await ReadRepositoryFileAsync("src/GmRelay.Web/Services/SessionService.cs");
+
+        Assert.Contains("external_user_id", service, StringComparison.Ordinal);
+        Assert.Contains("external_username", service, StringComparison.Ordinal);
+        Assert.Contains("platform", service, StringComparison.Ordinal);
+    }
+
     [Fact]
     public async Task AttendanceStatsFunction_ShouldReferenceExternalUsername()
     {