feat: add declarative bundle import and export compatibility

[sabino]

Description

Add a CLI-compatible declarative bundle compatibility layer to OLake UI so jobs can move between UI-managed configuration and repo-managed bundle workflows.

This PR adds backend import/export endpoints, Swagger/docs/examples, and UI affordances to import bundles and export an existing job back into a bundle. The import flow supports bundle archives, loose JSON files, and repeated folder selection for batch imports.

Fixes # (issue): N/A

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• go test ./internal/services/etl/...
• pnpm exec tsc --noEmit
• Rebuilt the local OLake UI container from this branch and verified the Jobs page import flow and Swagger endpoints at http://localhost:8000
• Verified the Jobs UI shows Import Bundle, the modal explains the compatibility layer, the row menu shows Export Bundle, and Swagger exposes the import/export bundle endpoints

Screenshots or Recordings

• Jobs page import modal with folder / JSON / archive options

• Job actions menu showing Export Bundle

• Swagger showing Import a declarative bundle and Export a declarative bundle

Related PR's (If Any):

• None

[CLAassistant]

All committers have signed the CLA.