ci: fix Prisma client generation race condition

Removed redundant prisma:generate commands from typecheck, test, and
build steps. The dedicated prisma-generate step already generates the
client, and all subsequent steps depend on it and share node_modules.

Multiple concurrent generation attempts were causing ENOENT errors
during file rename operations:
  Error: ENOENT: no such file or directory, rename
  '.../libquery_engine-linux-musl-openssl-3.0.x.so.node.tmp33'

This fix ensures Prisma client is generated exactly once per pipeline
run, eliminating the race condition.

Refs #CI-woodpecker

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.woodpecker.yml

@@ -52,7 +52,6 @@ steps:
       SKIP_ENV_VALIDATION: "true"
     commands:
       - *use_deps
-      - pnpm --filter "@mosaic/api" prisma:generate
       - pnpm typecheck
     depends_on:
       - prisma-generate
@@ -63,7 +62,6 @@ steps:
       SKIP_ENV_VALIDATION: "true"
     commands:
       - *use_deps
-      - pnpm --filter "@mosaic/api" prisma:generate
       - pnpm test || true # Non-blocking while fixing legacy tests
     depends_on:
       - prisma-generate
@@ -75,7 +73,6 @@ steps:
       NODE_ENV: "production"
     commands:
       - *use_deps
-      - pnpm --filter "@mosaic/api" prisma:generate
       - pnpm build
     depends_on:
       - typecheck # Only block on critical checks