Fix the action against the current prisma CLI (top-level deploy, 8.0.0-rc.9)

[kristof-siket]

What

Every released tag (v1.0.0–v1.5.0, the floating v1) and main are broken against the current prisma CLI. This PR makes the action work again, staying fully on Bun:

• Use the top-level commands. Since 8.0.0-rc.8 the deploy commands are top-level (prisma deploy); the composer subcommand family was removed, so the old invocation fails instantly with CLI.UNKNOWN_COMMAND in any repository with a current prisma devDependency (the action prefers the local bin).
• Bump the bunx fallback from 8.0.0-rc.7 (the last version with the old commands) to 8.0.0-rc.9, and sync the dead inline fallback in main.mjs.
• Require Bun >= 1.3.10, with a named error. Bun <= 1.3.9 omits Content-Length on the CLI's presigned-URL artifact upload, so every deploy fails with an opaque "Prisma artifact upload failed (HTTP 411)" (fixed in Bun 1.3.10). Runners get an old Bun from pins — package.json packageManager, .bun-version, or setup-bun's bun-version input — even though setup-bun defaults to latest. The action now checks bun --version up front and fails with the cause and the fix; an unreadable version only warns.
• README aligned with all of the above.

Verified

• All 48 tests pass (node --test tests/*.test.mjs).
• Verified end-to-end in the real pipeline (kristof-siket/my-app-prisma-blog, Bun >= 1.3.10 on the runner): production deploy under Bun green. Earlier verification with this command shape also covered preview stage deploys and OIDC auth.
• bunx -p prisma@8.0.0-rc.9 prisma --help confirms the top-level deploy command shape.
• Local Bun 1.3.11 deploys of a real Composer app succeed; the pinned-bun@1.3.9 fixture reproduced the HTTP 411.

Known issue (intentionally not addressed here)

mode: destroy cannot work against the current CLI: 8.0.0-rc.9 has no top-level destroy and no branch delete. The invocation is kept updated in form and the README documents the limitation; the teardown story is being followed up separately. In practice, Console-connected repositories get preview teardown from the platform's branch automation on branch deletion.

Follow-up

#13 (stacked on this) adds the release-policy guardrails: CLI version validation with a clear error, a canary workflow against prisma@next, and a compatibility matrix.

🤖 Generated with Claude Code

[kristof-siket]

Reworked after root-causing: the HTTP 411 was a Bun <= 1.3.9 bug (Content-Length omitted on the upload), not a CLI-side issue. The temporary Node invocation is gone — the action stays on Bun and instead enforces bun >= 1.3.10 with an error naming the bug. Pipeline re-verification under Bun is running now.