Closes #813
Fixes same bug as #793 but in CLI code path (PR #794 only fixed setup.ts, missed client.ts)

Summary

Two fixes:

1. migrations_dir path - migrations_dir in generated wrangler.json was set to .output/server/db/migrations/ but wrangler resolves paths relative to its config file location (.output/server/). This caused doubled paths like .output/server/.output/server/db/migrations/. Fixed by setting the path relative to wrangler.json: db/migrations/sqlite/.

2. D1 API endpoint - client.ts used wrong endpoint /d1/db/ instead of /d1/database/, causing POST method errors when running CLI commands against D1.

Regression introduced in #720.

StackBlitz

CLI Reproduction

git clone --depth 1 --filter=blob:none --sparse https://github.com/onmax/repros.git
cd repros && git sparse-checkout set nuxthub-813
cd nuxthub-813 && pnpm i && pnpm build
cat .output/server/wrangler.json | grep migrations_dir

Verify fix

git sparse-checkout add nuxthub-813-fix
cd ../nuxthub-813-fix && pnpm i && pnpm build
cat .output/server/wrangler.json | grep migrations_dir

The -fix folder uses pnpm patch to apply the fix locally.