feat: allow MongoDB backup of all databases when database name is empty

[krisvanmelis]

Summary

Closes #4186

• When the database field is left empty for MongoDB backups, mongodump runs without the -d flag, dumping all databases in the instance
• Other database types (Postgres, MySQL, MariaDB, libsql) still require a database name
• Added UI hint for MongoDB: "Leave empty to back up all databases"

Changes

• packages/server/src/utils/backups/utils.ts — Conditionally include -d flag in getMongoBackupCommand
• packages/server/src/db/schema/backups.ts — Relaxed database field validation from min(1) to allow empty string
• apps/dokploy/components/dashboard/database/backups/handle-backup.tsx — Added superRefine to require non-empty database for non-mongo types; added FormDescription hint for MongoDB

Test plan

• Create a MongoDB backup with an empty database name → should dump all databases
• Create a MongoDB backup with a specific database name → should dump only that database (existing behavior)
• Create a Postgres/MySQL/MariaDB backup with empty database → should show validation error
• Verify existing backups continue to work without changes

🤖 Generated with Claude Code

Greptile Summary

This PR adds support for MongoDB "dump all databases" mode by omitting the -d flag when the database field is empty, with corresponding frontend validation to require a database name only for non-MongoDB types. The frontend changes are clean and correct, but the server-side createSchema in backups.ts was relaxed globally (all types) without adding a compensating type-conditional refinement — meaning direct API calls can create broken backup configs for Postgres/MySQL/MariaDB/LibSQL with an empty database name that will silently fail at runtime.

Confidence Score: 4/5

Safe to merge after adding server-side databaseType-conditional validation to the backup schema.

There is one P1 defect: the server-side schema allows an empty database for all database types without enforcing the same databaseType-conditional rule as the frontend. A direct API call can persist a broken backup config that silently fails at execution time. All other changes (the mongodump flag logic, the UI hint, and the frontend superRefine) are correct.

packages/server/src/db/schema/backups.ts — createSchema needs a superRefine or per-schema refinement to reject empty database for non-mongo types.

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[krisvanmelis]

Fixed both issues flagged by Greptile:

P1 — Server-side databaseType-conditional validation: Added .superRefine() to the server-side createSchema in packages/server/src/db/schema/backups.ts that rejects an empty database for non-mongo database types. This mirrors the frontend validation so direct API calls can no longer persist broken backup configs.

P2 — Double space in mongodump command: Moved the trailing space into dbFlag in packages/server/src/utils/backups/utils.ts so there's no double space in the generated command when database is empty.