feat: deep linking for hosted URLs and openconcho:// scheme

Add /explore redirect route that maps Honcho's deep-link shape
(?workspace=...&view=...&session=...) onto our existing flat routes,
so any app.honcho.dev URL works against a self-hosted instance by
swapping the host.

Wire tauri-plugin-deep-link to register the openconcho:// scheme on
desktop and forward incoming URLs into the router on launch and at
runtime.

packages/desktop/src-tauri/tauri.conf.json

@@ -32,5 +32,13 @@
 		"security": {
 			"csp": null
 		}
+	},
+	"plugins": {
+		"deep-link": {
+			"mobile": [],
+			"desktop": {
+				"schemes": ["openconcho"]
+			}
+		}
 	}
 }