docs(python): define the Windows x64 runtime contract

Record win-x64 as the sole Windows Python carrier: node24-win-x64 builds a py3-none-win_amd64 wheel with dsh.exe, rg.exe, and both ConPTY addons; Windows arm64 remains explicitly unsupported. The note also pins native build ownership, shell-free pnpm launch, installed-wheel keyless/live gates, and the PowerShell-specific minimal snapshot.

Update the active SEA, sole-launcher, profile-runtime, installed-wheel, and publication decisions from three runtime wheels to four, preserving their existing rationale while linking the Windows extension. Contributor and runtime references now state the exact target, filenames, sidecars, snapshot ownership, and five-wheel release set in both languages.

python/sdk-runtime/README.md

@@ -8,7 +8,7 @@ Platform runtime wheel for the DeepSeek Harness Python SDK. It packages the norm
 
 The wheel installs a `dsh` console command and the `deepseek_harness_runtime` Python module. `dsh` forwards its arguments to the bundled executable and requires a non-empty `DSH_HOME`; it never falls back to `~/.dsh`.
 
-Production executables are named `deepseek-harness-sdk-runtime-<platform>-<arch>` under the module's `runtime/` directory. Linux and macOS wheels include a target-native `-rg` sidecar; macOS also includes `-spawn-helper` for `node-pty`. Published targets are Linux x64, Linux arm64, and macOS arm64. The wheel tag and payload must match exactly.
+Production executables are named `deepseek-harness-sdk-runtime-<platform>-<arch>` under the module's `runtime/` directory; Windows uses the `.exe` suffix. Linux and macOS wheels include a target-native `-rg` sidecar, Windows includes `-rg.exe`, and macOS also includes `-spawn-helper` for `node-pty`. Published targets are Linux x64, Linux arm64, macOS arm64, and Windows x64. The wheel tag and payload must match exactly; no Windows arm64 wheel is published.
 
 Repository builds also materialize a dev-only `runtime/node/` carrier. It runs `node runtime/node/node_modules/@deepseek-ai/dsh/lib/bin.js` on system Node 22.19 or newer. It is never selected automatically and is excluded from wheels and sdists.
 
@@ -25,7 +25,7 @@ Unsupported platforms and missing executables or sidecars raise `FileNotFoundErr
 
 ## Packaged profile resolution
 
-`dsh` initializes shipped profiles under the explicit home, composes their bundle patches, and loads bundled plugins from the executable's virtual filesystem. Because operating-system symlinks cannot enter that filesystem, packaged launches maintain small real ESM proxy packages under `$DSH_HOME/profiles/node_modules`. Each proxy mirrors explicit runtime exports, records the original package identity, and re-exports the virtual module URL. Built-in rows and external plugin peers therefore share one Cordis/module instance. Native shared libraries are packaged with native addons, while ripgrep and the macOS PTY helper remain executable sidecars.
+`dsh` initializes shipped profiles under the explicit home, composes their bundle patches, and loads bundled plugins from the executable's virtual filesystem. Because operating-system symlinks cannot enter that filesystem, packaged launches maintain small real ESM proxy packages under `$DSH_HOME/profiles/node_modules`. Each proxy mirrors explicit runtime exports, records the original package identity, and re-exports the virtual module URL. Built-in rows and external plugin peers therefore share one Cordis/module instance. Native shared libraries and Windows ConPTY addons are packaged with native addons, while ripgrep and the macOS PTY helper remain executable sidecars.
 
 External profile management uses `dsh plugin --profile <name> ...`. That command requires `pnpm` on `PATH`; ordinary SDK/profile execution does not.