Add Tauri launcher with Svelte UI

- Accounts: panel login/sign-up, Microsoft device-code sign-in, offline
  play; tokens encrypted with a key kept in the OS credential store
- Home: instance rail, live server status, news feed, social links,
  Play button with download progress, speed and ETA
- Full settings: accounts, memory/resolution/after-launch behaviour,
  Java and GC presets, Minecraft keybind editor applied to options.txt,
  theme overrides, storage manager, self-update via GitHub releases
- Game console, crash dialog with hints, per-instance overrides
- Live admin branding (colours, fonts, backgrounds, custom CSS)
- Online install tests for vanilla/Fabric/Quilt/Forge/NeoForge (CI)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

launcher/src-tauri/Cargo.toml

@@ -0,0 +1,40 @@
+[package]
+name = "scopenet-launcher"
+description = "ScopeNet Minecraft launcher"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[lib]
+name = "scopenet_launcher_lib"
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[build-dependencies]
+tauri-build = { version = "2", features = [] }
+
+[dependencies]
+scopenet-shared.workspace = true
+scopenet-core.workspace = true
+anyhow.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+tokio.workspace = true
+reqwest.workspace = true
+futures.workspace = true
+uuid.workspace = true
+base64.workspace = true
+rand.workspace = true
+tracing.workspace = true
+tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
+tauri = { version = "2", features = [] }
+tauri-plugin-dialog = "2"
+tauri-plugin-opener = "2"
+tauri-plugin-single-instance = "2"
+chacha20poly1305 = "0.10"
+
+# Secrets are encrypted with a key kept in the OS credential store.
+[target.'cfg(windows)'.dependencies]
+keyring = { version = "3", features = ["windows-native"] }
+
+[target.'cfg(target_os = "macos")'.dependencies]
+keyring = { version = "3", features = ["apple-native"] }