remove minikube from Makefile (#1036)

## Summary

- Remove minikube-only targets (`local-url`, `check-minikube`,
`_build-and-load`) and minikube references from remaining targets
(`local-down`, `local-status`, `local-test-quick`, `makefile-health`,
`check-local-context`, `_show-access-info`)
- Add per-component kind reload targets: `kind-reload-backend`,
`kind-reload-frontend`, `kind-reload-operator`
- Add deprecation aliases for removed targets (`local-up`,
`local-clean`, `local-rebuild`,
`local-reload-backend/frontend/operator`) that print a warning and
delegate to the kind equivalent
- Follow-up issue #1080 tracks updating docs that still reference the
old target names

Fixes #992

## Test plan

- [x] `make help` displays correctly with updated examples
- [x] `make help` still lists `local-up` (with deprecation note)
- [x] `make kind-up` still works as the local dev entrypoint
- [x] `make kind-rebuild` still works for reloading components
- [x] `make kind-reload-backend` / `kind-reload-frontend` /
`kind-reload-operator` dry-run succeeds
- [x] `make local-up` prints deprecation warning and delegates to
`kind-up`
- [x] `make local-status` correctly detects kind clusters
- [x] `make local-test-quick` correctly detects kind clusters
- [x] `make makefile-health` runs without errors
- [x] No minikube references remain in Makefile (except one comment
documenting that the deprecated aliases replace the old minikube-based
workflow)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: ktdreyer