feat(v3): migrate workspace to API, Tauri desktop, and v3 crates; remove legacy MCP stack

- Add apps/api, desktop Tauri shell, domain/application/crypto/device-auth/infrastructure-db
- Replace desktop-daemon vault integration; drop secrets-core and secrets-mcp*
- Ignore apps/desktop/dist and generated Tauri icons; document icon/dist steps in AGENTS.md
- Apply rustfmt; fix clippy (collapsible_if, HTTP method as str)

apps/desktop/src-tauri/Cargo.toml

@@ -0,0 +1,32 @@
+[package]
+name = "secrets-desktop"
+version = "3.0.0"
+edition.workspace = true
+
+[build-dependencies]
+tauri-build.workspace = true
+
+[dependencies]
+anyhow.workspace = true
+axum.workspace = true
+chrono.workspace = true
+hex.workspace = true
+sqlx.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+tauri.workspace = true
+tokio.workspace = true
+reqwest.workspace = true
+sha2.workspace = true
+url.workspace = true
+uuid.workspace = true
+base64 = "0.22.1"
+
+secrets-client-integrations = { path = "../../../crates/client-integrations" }
+secrets-crypto = { path = "../../../crates/crypto" }
+secrets-device-auth = { path = "../../../crates/device-auth" }
+secrets-domain = { path = "../../../crates/domain" }
+
+[[bin]]
+name = "Secrets"
+path = "src/main.rs"