feat(backups): add rclone destination providers

[partyplatter08-lab]

/claim #416

Fixes #416.

Demo: attached ui-destination-demo.mp4 shows the Add Destination provider selector and the FTP, SFTP, Google Drive, and OneDrive field sets.

Summary

• Adds rclone-backed backup destination support for FTP, SFTP, Google Drive, and OneDrive while keeping existing S3-compatible destinations on the same schema.
• Centralizes provider-aware rclone flag and remote path generation, including shell quoting for destination values.
• Wires the provider-aware helpers through database, compose, web server, and volume backup upload, retention, file listing, and restore paths.
• Updates the destination settings UI from S3-only wording to provider-aware fields and validation.
• Adds focused coverage for provider mapping, remote path construction, backend flags, and shell quoting.

Validation

• corepack pnpm exec biome check $(git diff --name-only origin/canary..HEAD)
• corepack pnpm --filter=dokploy exec vitest --config __test__/vitest.config.ts __test__/utils/backups.test.ts --run
• corepack pnpm --filter=server run typecheck
• corepack pnpm --filter=dokploy run typecheck
• corepack pnpm --filter=dokploy run build-server
• corepack pnpm --filter=dokploy run build-next
• Local rclone command-generation smoke for S3, FTP, SFTP, Google Drive, and OneDrive upload/list command strings.
• Chrome-captured UI demo/screenshots for the Add Destination provider selector and provider-specific fields.