[cmd] add interactive TUI for apoxy k8s install

Replace silent apply with a plan-preview-confirm-progress flow:
- Build a resource plan showing create/update/unchanged for each resource
- Show colorized line-based diffs for updates (LCS-based, not character-level)
- Bubbletea inline y/N confirmation with kube context name displayed
- Spinner-per-resource progress during apply
- Plain text fallback for non-TTY (requires --yes)
- Extract dry-run into separate function (behavior unchanged)
- Add --yes/-y flag to skip confirmation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dilyevsky