fix(database): include the Prisma CLI in production builds (#3843)

## Summary

The Prisma CLI was missing from production builds of the webapp image,
so anything that shells out to `prisma` at startup failed. The container
entrypoint and the standalone migration step both run `prisma migrate
deploy` / `prisma migrate status`, and those broke with `Command
"prisma" not found`.

## Fix

`prisma` was a `devDependency` of `@trigger.dev/database`. It had only
been landing in the pruned `--prod` install as a side effect of pnpm
auto-installing it as a peer of `@prisma/client`. A recent dependency
change shifted peer resolution so prisma stopped being materialized into
the production tree, and the CLI disappeared from the image.

Moving `prisma` into `dependencies` of `@trigger.dev/database` makes the
CLI an explicit part of production installs. It lands in the webapp
image only: the separately deployed supervisor, coordinator, and
provider images don't reach the database package in their production
trees (`core` only `devDepends` on it, so it isn't transitive), so
they're unaffected.

Verified against a locally built production image: `pnpm --filter
@trigger.dev/database exec prisma --version` now resolves the CLI and
the schema engine instead of failing.

Author: ericallam

.server-changes/include-prisma-cli-in-prod-image.md

@@ -0,0 +1,6 @@
+---
+area: webapp
+type: fix
+---
+
+Fix database migrations failing to run in the production image because the Prisma CLI was missing from the build.

internal-packages/database/package.json

@@ -6,11 +6,11 @@
   "types": "./dist/index.d.ts",
   "dependencies": {
     "@prisma/client": "6.14.0",
-    "decimal.js": "^10.6.0"
+    "decimal.js": "^10.6.0",
+    "prisma": "6.14.0"
   },
   "devDependencies": {
     "@types/decimal.js": "^7.4.3",
-    "prisma": "6.14.0",
     "rimraf": "6.0.1"
   },
   "scripts": {