release: drift guard that the cloudflare target ignores dataDir (RFC-0046 §11b) #239

RFC-0046 §11b classes cloudhal.json dataDir as runtime for deploy --release: a release bundle is built in CI, so whatever dataDir it bakes in is the CI build's absolute path, and the deployed Site Worker must never read it. §11b asks for a drift guard: "an astro-renderer test shows that the cloudflare target ignores dataDir. If it does not, the integration stops emitting dataDir for that target."

#238 leaves this guard out. Today the cloudhal() integration resolves dataDir to an absolute path and puts it into virtual:cloudhal/config on every target (packages/astro-renderer/src/integration.ts, astro:config:setup). runtime.ts (localStore(config.dataDir)) and the comments middleware read it on Node targets. Showing that nothing reachable from the Cloudflare entry reads it means one of two things:

• trace the cloudflare entry's imports and prove it, which is fragile; or
• stop emitting dataDir for target: "cloudflare" and run the workerd suites (packages/cli/test/cloudflare-*.test.ts, which build the starter) to show nothing breaks.

Done when

• The cloudflare target's virtual:cloudhal/config carries no dataDir, or a test proves the cloudflare entry never reads it.
• The cli workerd suites pass.
• RFC-0046 §11b's runtime class for dataDir cites the test.

Refs #227, #238.