Add versioned DB migrations, startup error dialog and native basics

rusqlite_migration with a VACUUM INTO backup before upgrading; M2 adds GST
registration, snapshot, cancellation and draft columns and backfills
snapshots for existing invoices. Startup failures now show a native dialog
instead of exiting silently. Adds single-instance and window-state plugins,
minimum window 960x600, embedBootstrapper, DMABUF workaround on Linux and
xbps dependency updates.

src-tauri/Cargo.lock

@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "adler2"
@@ -2887,6 +2887,16 @@ dependencies = [
  "sqlite-wasm-rs",
 ]
 
+[[package]]
+name = "rusqlite_migration"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "03451d4dc523c0a96d9e412c574670b3f5f184c3988b77a435876be25477bbd3"
+dependencies = [
+ "log",
+ "rusqlite",
+]
+
 [[package]]
 name = "rustc-hash"
 version = "2.1.3"
@@ -3658,6 +3668,37 @@ dependencies = [
  "zbus",
 ]
 
+[[package]]
+name = "tauri-plugin-single-instance"
+version = "2.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee2c8fe2d6b75caed0153f91eda30ea1dea3bfb6710d5adb80456d2c035a569d"
+dependencies = [
+ "serde",
+ "serde_json",
+ "tauri",
+ "thiserror 2.0.21",
+ "tokio",
+ "tracing",
+ "windows-sys 0.61.2",
+ "zbus",
+]
+
+[[package]]
+name = "tauri-plugin-window-state"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d6815cab7b212f9cfe16a9d79d8d22f9e14159e4a9460f7dec1467167a008e3"
+dependencies = [
+ "bitflags 2.13.2",
+ "log",
+ "serde",
+ "serde_json",
+ "tauri",
+ "tauri-plugin",
+ "thiserror 2.0.21",
+]
+
 [[package]]
 name = "tauri-runtime"
 version = "2.12.1"
@@ -4196,12 +4237,16 @@ dependencies = [
  "base64 0.22.1",
  "chrono",
  "rusqlite",
+ "rusqlite_migration",
  "serde",
  "serde_json",
  "tauri",
  "tauri-build",
  "tauri-plugin-dialog",
  "tauri-plugin-opener",
+ "tauri-plugin-single-instance",
+ "tauri-plugin-window-state",
+ "tempfile",
  "thiserror 2.0.21",
  "uuid",
 ]