Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

docs/README.md

@@ -0,0 +1,15 @@
+# EmDash Docs
+
+Documentation site for EmDash, built with [Starlight](https://starlight.astro.build).
+
+## Development
+
+```bash
+pnpm dev
+```
+
+## Build
+
+```bash
+pnpm build
+```