refactor(prompt): extract file path logic and implement auto-import on first launch (#214)

- Extract prompt file path logic to dedicated prompt_files module
- Refactor PromptService to use centralized path resolution
- Implement auto-import for existing prompt files on first startup
- Add comprehensive unit tests for auto-import functionality

src-tauri/Cargo.lock

@@ -576,6 +576,7 @@ dependencies = [
  "rquickjs",
  "serde",
  "serde_json",
+ "serial_test",
  "tauri",
  "tauri-build",
  "tauri-plugin-dialog",
@@ -585,6 +586,7 @@ dependencies = [
  "tauri-plugin-single-instance",
  "tauri-plugin-store",
  "tauri-plugin-updater",
+ "tempfile",
  "thiserror 1.0.69",
  "tokio",
  "toml 0.8.2",
@@ -3727,6 +3729,15 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "scc"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46e6f046b7fef48e2660c57ed794263155d713de679057f2d0c169bfc6e756cc"
+dependencies = [
+ "sdd",
+]
+
 [[package]]
 name = "schemars"
 version = "0.8.22"
@@ -3790,6 +3801,12 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
+[[package]]
+name = "sdd"
+version = "3.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "490dcfcbfef26be6800d11870ff2df8774fa6e86d047e3e8c8a76b25655e41ca"
+
 [[package]]
 name = "seahash"
 version = "4.1.0"
@@ -3962,6 +3979,31 @@ dependencies = [
  "syn 2.0.106",
 ]
 
+[[package]]
+name = "serial_test"
+version = "3.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b258109f244e1d6891bf1053a55d63a5cd4f8f4c30cf9a1280989f80e7a1fa9"
+dependencies = [
+ "futures",
+ "log",
+ "once_cell",
+ "parking_lot",
+ "scc",
+ "serial_test_derive",
+]
+
+[[package]]
+name = "serial_test_derive"
+version = "3.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d69265a08751de7844521fd15003ae0a888e035773ba05695c5c759a6f89eef"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.106",
+]
+
 [[package]]
 name = "serialize-to-javascript"
 version = "0.1.2"