fix: add +crt-static to Windows rustflags to eliminate vcruntime140.dll dependency (#407)

The Windows-specific `[target.'cfg(target_os = "windows")']` rustflags
sections in `.cargo/config.toml.disabled` were **overriding** the global
`[build].rustflags`, silently dropping `-Ctarget-feature=+crt-static`.
This caused the shipped `pet.exe` to dynamically link `VCRUNTIME140.dll`
and several UCRT DLLs, breaking Python environment detection on
enterprise machines without the VC++ Redistributable installed.

**Changes:**
- Add `-Ctarget-feature=+crt-static` to both Windows target-specific
`rustflags` sections
- Narrow the global `[build]` section to `cfg(target_os = \"linux\")` to
avoid ambiguity

**Verified locally:** rebuilt `pet.exe` with the fix —
`VCRUNTIME140.dll` and all `api-ms-win-crt-*` imports are eliminated.

Fixes #406

Author: karthiknadig

.cargo/config.toml.disabled

@@ -4,17 +4,16 @@
 # [registries.ms-crates-io]
 # index = "sparse+https://pkgs.dev.azure.com/vscode/_packaging/crates/Cargo/index/"
 
-# Windows: -Ctarget-feature=+crt-static: Statically link the CRT (required to link the spectre-mitigated CRT).
-# Other: -Ctarget-feature=+crt-static: Statically link the CRT
-[build]
+# Linux: -Ctarget-feature=+crt-static: Statically link the CRT.
+[target.'cfg(target_os = "linux")']
 rustflags = ["-Ctarget-feature=+crt-static"]
 
 # -Cehcont_guard: Enable EH Continuation Metadata (https://learn.microsoft.com/en-us/cpp/build/reference/guard-enable-eh-continuation-metadata).
 # -Ccontrol-flow-guard: Enable Control Flow Guard, needed for OneBranch's post-build analysis (https://learn.microsoft.com/en-us/cpp/build/reference/guard-enable-control-flow-guard).
 # -Ctarget-feature=+crt-static: Statically link the CRT (required to link the spectre-mitigated CRT).
 [target.'cfg(target_os = "windows")']
-rustflags = ["-Cehcont_guard", "-Ccontrol-flow-guard"]
+rustflags = ["-Ctarget-feature=+crt-static", "-Cehcont_guard", "-Ccontrol-flow-guard"]
 
 # -Clink-args=/DYNAMICBASE /CETCOMPAT: Enable "shadow stack" (https://learn.microsoft.com/en-us/cpp/build/reference/cetcompat)
 [target.'cfg(all(target_os = "windows", any(target_arch = "i686", target_arch = "x86_64")))']
-rustflags = ["-Clink-args=/DYNAMICBASE /CETCOMPAT"]
+rustflags = ["-Ctarget-feature=+crt-static", "-Clink-args=/DYNAMICBASE /CETCOMPAT"]