feat(interpreters): add an existing Python virtual environment as an interpreter (#2076)

Refs #1907

Add Python Interpreter → Existing environment: Browse picks the environment folder, which is resolved right away (pyvenv.cfg, bin/python or Scripts\python.exe) and added to the interpreter list as "Python X.Y (<env name>)", then remembered. Picking the folder rather than the executable keeps the environment's identity, since the native file picker resolves the venv's python symlink to the base interpreter. Works for `python -m venv` and uv environments; a broken environment shows an error instead of being added. Probing runs off the command thread.

Co-authored-by: Inf1mum <[email protected]>

src/bindings.ts

@@ -823,6 +823,26 @@ export const commands = {
 	jdkDownload: (vendor: string, version: number, location: string | null, request: RequestId, onEvent: Channel<InstallEvent>) => typedError<Sdk, IdeError>(__TAURI_INVOKE("jdk_download", { vendor, version, location, request, onEvent })),
 	/**  Installed interpreters / toolchains of `kind`; project-local ones first. */
 	sdkDetect: (kind: SdkKind) => typedError<Sdk[], IdeError>(__TAURI_INVOKE("sdk_detect", { kind })),
+	/**  An existing Python executable or virtualenv folder as an SDK; `None` if Python cannot run. */
+	sdkPythonInterpreter: (path: string) => typedError<{
+	/**
+	 *  Executable (`python`, `node`, `pnpm`) or directory (Rust toolchain bin
+	 *  dir, GOROOT, TypeScript `lib` dir) that the setting stores.
+	 */
+	path: IpcPath,
+	/**  Display name, e.g. `Python 3.12 (.venv)` or `stable-aarch64-apple-darwin`. */
+	name: string,
+	version: string | null,
+	/**
+	 *  Where it was found: `venv` | `system` | `pyenv` | `conda` | `uv` | `nvm` |
+	 *  `rustup` | `bundled` | `workspace` | `path` …
+	 */
+	source: string,
+	/**  Environment / toolchain root (virtualenv dir, rustup toolchain dir, GOROOT). */
+	home: IpcPath | null,
+	/**  Rust standard library sources, Go default GOPATH. */
+	extra: IpcPath | null,
+} | null, IdeError>(__TAURI_INVOKE("sdk_python_interpreter", { path })),
 	/**  The interpreter the project uses: the configured one, else its virtualenv. */
 	sdkPythonEffective: (near: string | null) => typedError<string | null, IdeError>(__TAURI_INVOKE("sdk_python_effective", { near })),
 	/**  The PHP interpreter chosen in Settings › Languages & Frameworks › PHP; `None`: the `php` on `PATH`. */