feat(api): Add deployment plan validation/dry-run endpoint #39
Description
Context
No way to validate a deployment plan before executing it. Users discover resource conflicts, missing templates, or network overlaps only at execution time.
Requirements
POST /v0/admin/deployments/validate— Accept a deployment plan and validate against live Proxmox state- Check: template existence, VM ID availability, sufficient CPU/RAM/disk, network/bridge conflicts, VLAN overlap
- Return structured validation result with errors and warnings per step
- No side effects — read-only operation
Priority
Important — Phase 6. Blocks: U8 (dry-run/preview mode in UI).
References
- Gap analysis:
gap-analysis.mdissue B8