feat: add DSH IDE open-file references

vscode-extension/README.md

@@ -0,0 +1,20 @@
+# DSH Open File Bridge for VS Code
+
+This companion publishes the local disk files represented by all VS Code tabs. It uses `window.tabGroups.all`, so background tabs are included; text diff tabs contribute both local sides. Untitled and non-file URI schemes are excluded.
+
+## Development
+
+```powershell
+pnpm install
+pnpm test
+pnpm build
+pnpm package
+```
+
+Install the generated `.vsix` with **Extensions: Install from VSIX...** or:
+
+```powershell
+code --install-extension prophet-coop-with-dsh-0.1.0.vsix
+```
+
+The extension writes no source content. It updates a per-instance JSON snapshot under `%LOCALAPPDATA%\Prophet\dsh-plugin-coop-with-vs\v1\instances`, heartbeats every 15 seconds, and removes the file on clean deactivation.