Initial commit: Triple-C app, container, and CI

Tauri v2 desktop app (React/TypeScript + Rust) for managing
containerized Claude Code environments. Includes Gitea Actions
workflow for building and pushing the sandbox container image,
and a BUILDING.md guide for manual app builds on Linux and Windows.

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

app/src-tauri/tauri.conf.json

@@ -0,0 +1,38 @@
+{
+  "$schema": "https://raw.githubusercontent.com/tauri-apps/tauri/dev/crates/tauri-cli/schema.json",
+  "productName": "Triple-C",
+  "version": "0.1.0",
+  "identifier": "com.triple-c.app",
+  "build": {
+    "beforeDevCommand": "npm run dev",
+    "devUrl": "http://localhost:1420",
+    "beforeBuildCommand": "npm run build",
+    "frontendDist": "../dist"
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "Triple-C",
+        "width": 1200,
+        "height": 800,
+        "resizable": true,
+        "fullscreen": false,
+        "minWidth": 800,
+        "minHeight": 600
+      }
+    ],
+    "security": {
+      "csp": null
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": "all",
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/128x128@2x.png"
+    ]
+  },
+  "plugins": {}
+}