Add Build Solution (MSBuild) with live output

find_sln locates a .sln in the working folder; build_sln locates MSBuild
via vswhere and builds the solution's default config (compiles the UE game
module for Unreal projects), streaming output as build-log events. A build
overlay shows the live log with error/warning coloring and a status. Wired
into Tools (Ctrl+B) and the Working-folder right-click menu when a .sln is
found. New strings translated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/p4.ts

@@ -73,6 +73,8 @@ export const p4 = {
   undoChange: (change: string) => invoke<string>("p4_undo_change", { change }),
   openInExplorer: (target: string) => invoke<void>("open_in_explorer", { target }),
   findUproject: (scope: string) => invoke<string>("find_uproject", { scope }),
+  findSln: (scope: string) => invoke<string>("find_sln", { scope }),
+  buildSln: (path: string) => invoke<string>("build_sln", { path }),
   launchFile: (path: string) => invoke<void>("launch_file", { path }),
   openInVscode: (depot: string) => invoke<void>("open_in_vscode", { depot }),
   readDepot: async (depot: string): Promise<ArrayBuffer> => {