feat(desktop): bundle sprout-acp and sprout-mcp-server as Tauri sidecars (#362)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/src-tauri/.gitignore

@@ -5,3 +5,6 @@
 # Generated by Tauri
 # will have schema files for capabilities auto-completion
 /gen/schemas
+
+# Sidecar binaries (built by scripts/bundle-sidecars.sh)
+/binaries/

desktop/src-tauri/tauri.conf.json

@@ -34,6 +34,7 @@
   "bundle": {
     "active": true,
     "targets": "all",
+    "externalBin": ["binaries/sprout-acp", "binaries/sprout-mcp-server"],
     "icon": [
       "icons/32x32.png",
       "icons/128x128.png",

justfile

@@ -87,6 +87,12 @@ desktop-tauri-fmt-check:
 
 # Check the desktop Tauri Rust crate compiles
 desktop-tauri-check:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    TARGET=$(rustc -vV | sed -n 's|host: ||p')
+    mkdir -p desktop/src-tauri/binaries
+    touch "desktop/src-tauri/binaries/sprout-acp-$TARGET"
+    touch "desktop/src-tauri/binaries/sprout-mcp-server-$TARGET"
     cargo check --manifest-path {{desktop_tauri_manifest}}
 
 # Run desktop checks suitable for CI / pre-push