Add wrangler.jsonc so the assets deploy finds dist/

The Python build now succeeds on Cloudflare, but the deploy step
(`wrangler versions upload`) failed with no entry point. Declare an
assets-only Worker pointing at ./dist so the deploy uploads the built site.
Also switch the local `make preview` to `wrangler dev` to match.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: bobthemighty

Makefile

@@ -7,7 +7,7 @@ serve: build
 	cd dist && python -m http.server 8899
 
 preview: build
-	npx wrangler pages dev dist
+	npx wrangler dev
 
 watch-build:
 	ls **/*.md **/*.html **/*.xml *.py | entr ./generate-html.py

wrangler.jsonc

@@ -0,0 +1,7 @@
+{
+  "name": "cosmicpython",
+  "compatibility_date": "2026-06-14",
+  "assets": {
+    "directory": "./dist"
+  }
+}