feat: persistently store backup state

Cargo.lock

@@ -15,6 +15,8 @@ dependencies = [
  "chrono",
  "clap",
  "flate2",
+ "serde",
+ "serde_json",
  "signal-hook",
  "tar",
 ]
@@ -123,6 +125,7 @@ dependencies = [
  "iana-time-zone",
  "js-sys",
  "num-traits",
+ "serde",
  "time",
  "wasm-bindgen",
  "winapi",
@@ -292,6 +295,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "453ad9f582a441959e5f0d088b02ce04cfe8d51a8eaf077f12ac6d3e94164ca6"
+
 [[package]]
 name = "js-sys"
 version = "0.3.63"
@@ -384,6 +393,43 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "ryu"
+version = "1.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f91339c0467de62360649f8d3e185ca8de4224ff281f66000de5eb2a77a79041"
+
+[[package]]
+name = "serde"
+version = "1.0.164"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e8c8cf938e98f769bc164923b06dce91cea1751522f46f8466461af04c9027d"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.164"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9735b638ccc51c28bf6914d90a2e9725b377144fc612c49a611fddd1b631d68"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.96"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "057d394a50403bcac12672b2b18fb387ab6d289d957dab67dd201875391e52f1"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "signal-hook"
 version = "0.3.15"