dogfood: verify and enable Prisma-on-Bun so examples/blog runs on the Bun runtime

[vivek7405]

Problem

examples/blog is the one in-repo app that uses Prisma (SQLite). To run it on the Bun runtime we need Prisma working under Bun, which is the historical rough edge (the query engine + the generated-client resolution). When I probed the blog under Bun it failed before reaching a query, but on the #521 resolution divergence (a stale @prisma/client@7.8.0 from the Bun global cache with no generated .prisma/client/default), so Prisma-on-Bun itself is still UNVERIFIED for our setup.

Design / approach

Once #521 lands (Bun resolves the workspace + the generated client), verify and enable Prisma-on-Bun for the blog:

• Confirm prisma generate produces a client Bun can load and query against the blog dev.db (count/read/write round-trip).
• If the bundled query engine path needs a Bun-specific binary target or engine type, configure it in schema.prisma (binaryTargets) or switch engine type as needed.
• Boot the blog under Bun and serve its DB-backed home route; run the blog e2e against the Bun-served app.
• If Prisma-on-Bun proves not viable yet, document the blocker and keep the blog on Node (the framework supports both; the deployed blog can stay Node while the content apps move to Bun).

Depends on #521 and follows #522 in the sequence.

Acceptance criteria

• Prisma client generates and round-trips a query (read + write) against the blog dev.db under Bun.
• examples/blog boots and serves its DB-backed routes under bun --bun run start.
• The blog e2e passes against the Bun-served app (or the blocker is documented and the blog stays on Node with a clear reason).
• Docs updated (deployment) on the blog runtime decision.
• Depends on dogfood: link the workspace under Bun so monorepo apps resolve local @webjsdev/* + Prisma #521.

[vivek7405]

Update: Prisma reads already work on Bun, write-path + deploy remain

Confirmed while investigating #521: the blog's DB-backed home page (a real Prisma read listing posts) serves 200 under Bun 1.3.14, with the client resolving to the npm-installed 5.22.0 + its generated engine. So the historical "does Prisma load and query on Bun" risk is cleared for the read path; my earlier failure was a probe-from-/tmp artifact, not a Prisma-on-Bun problem.

Remaining to actually close this:

• Verify a WRITE path (create/update a post via a server action) round-trips under Bun, not just reads.
• Run the blog e2e against the Bun-served app.
• Decide + apply the blog's Railway deploy runtime (Bun vs stay Node), coordinated with dogfood: run the 3 content apps (website, docs, ui-website) on the Bun runtime #522.