feat(mysql): native SQL execution — fix #41 type decoding, in-process restore, .sql open-with (#42)

Fixes #41.

MySQL columns now decode by their declared type instead of a blind try_get chain,
so every non-string type (integers, DECIMAL, BIT, YEAR, DATE/TIME/DATETIME/TIMESTAMP)
renders its value instead of NULL. MySQL restore runs in-process over the sqlx driver
(no bundled MariaDB client, so MySQL 8 caching_sha2_password works) and the Clean toggle
is implemented. .sql files can be opened with Gridline from the OS file manager.

Verified: cargo test --lib 442 passed / 0 failed; bun run test 133 files / 1151 tests
exit 0; tsc clean; both live MySQL 8 integration tests pass with the bundled CLI hidden.

desktop/src-tauri/Cargo.lock

@@ -339,6 +339,19 @@ dependencies = [
  "smallvec",
 ]
 
+[[package]]
+name = "bigdecimal"
+version = "0.4.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8fa3f3d8cbf4dffcfe4991de61d012bef509a409ecbe9dd41049bfe32b4d4653"
+dependencies = [
+ "autocfg",
+ "libm",
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+]
+
 [[package]]
 name = "bit-set"
 version = "0.8.0"
@@ -1809,6 +1822,7 @@ dependencies = [
  "tauri-plugin-fs",
  "tauri-plugin-keyring-store",
  "tauri-plugin-opener",
+ "tauri-plugin-single-instance",
  "tokio",
  "tokio-postgres",
  "tokio-postgres-rustls",
@@ -4425,8 +4439,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a999083c1af5b5d6c071d34a708a19ba3e02106ad82ef7bbd69f5e48266b613b"
 dependencies = [
  "atoi",
+ "bigdecimal",
  "byteorder",
  "bytes",
+ "chrono",
  "crc",
  "crossbeam-queue",
  "either",
@@ -4507,9 +4523,11 @@ checksum = "5afe4c38a9b417b6a9a5eeffe7235d0a106716495536e7727d1c7f4b1ff3eba6"
 dependencies = [
  "atoi",
  "base64 0.22.1",
+ "bigdecimal",
  "bitflags 2.13.1",
  "byteorder",
  "bytes",
+ "chrono",
  "crc",
  "digest 0.10.7",
  "dotenvy",
@@ -4549,8 +4567,10 @@ checksum = "b1dbb157e65f10dbe01f729339c06d239120221c9ad9fa0ba8408c4cc18ecf21"
 dependencies = [
  "atoi",
  "base64 0.22.1",
+ "bigdecimal",
  "bitflags 2.13.1",
  "byteorder",
+ "chrono",
  "crc",
  "dotenvy",
  "etcetera",
@@ -4566,6 +4586,7 @@ dependencies = [
  "log",
  "md-5 0.10.6",
  "memchr",
+ "num-bigint",
  "once_cell",
  "rand 0.8.7",
  "serde",
@@ -4586,6 +4607,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b2cdd83c008a622d94499c0006d8ee5f821f36c89b7d625c900e5dc30b5c5ee"
 dependencies = [
  "atoi",
+ "chrono",
  "flume",
  "futures-channel",
  "futures-core",
@@ -5020,6 +5042,22 @@ dependencies = [
  "zbus",
 ]
 
+[[package]]
+name = "tauri-plugin-single-instance"
+version = "2.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db817fe9295e19b7d8357e900af31edb93703dd9fb6de524b007b47b6afc63b0"
+dependencies = [
+ "serde",
+ "serde_json",
+ "tauri",
+ "thiserror 2.0.19",
+ "tokio",
+ "tracing",
+ "windows-sys 0.60.2",
+ "zbus",
+]
+
 [[package]]
 name = "tauri-runtime"
 version = "2.11.3"