feat: implement phases 3-5 of Arma 3 UX enhancement plan

Phase 3 - Mod display names + split-pane selector:
- Parse mod.cpp/meta.cpp for display_name and workshop_id
- Rewrite ModList as two-pane available/selected interface

Phase 4 - Player kick/ban from Players tab:
- Add get_by_slot() to PlayerRepository
- Add get_rcon_client() class method to ThreadRegistry
- Add /players/{slot_id}/kick and /ban endpoints
- Rewrite PlayerTable with kick/ban modals and ban presets

Phase 5 - Historical log file browser:
- Add list_log_files() and get_log_file_path() to RPTParser
- Add logfiles_router with GET/download/DELETE endpoints
- Update LogViewer with collapsible log files section (download + delete)

backend/main.py

@@ -168,6 +168,7 @@ def create_app() -> FastAPI:
     from core.servers.bans_router import router as bans_router
     from core.servers.missions_router import router as missions_router
     from core.servers.mods_router import router as mods_router
+    from core.servers.logfiles_router import router as logfiles_router
     from core.websocket.router import router as ws_router
 
     app.include_router(auth_router, prefix="/api")
@@ -178,6 +179,7 @@ def create_app() -> FastAPI:
     app.include_router(bans_router, prefix="/api")
     app.include_router(missions_router, prefix="/api")
     app.include_router(mods_router, prefix="/api")
+    app.include_router(logfiles_router, prefix="/api")
     app.include_router(ws_router)
 
     return app