fix(cmd): support control plane API implementation get

[rspurgeon]

Summary

• support control-plane implementation union values when filtering by implementation ID
• populate control-plane implementation table rows and detail views
• add unit coverage for control-plane formatting and both implementation variants
• expand the E2E scenario with list, get-by-ID, and not-found coverage

Testing

• go fix ./...
• make format
• make build
• make test
• golangci-lint run ./internal/cmd/root/products/konnect/api
• make lint (fails on pre-existing generated mock/portal-client line-length and misspelling findings, plus two pre-existing staticcheck findings)

Closes #2006

[rspurgeon]

/ksai review

[github-actions]

Run report (federated)

Item	Detail
Conclusion	success
Reviewed commit	b123ab36e955522c7b505bfeb8e5d3af61587ade
Model	claude-sonnet-5 (effort high)
Arm source	triage
Triage	4 files, 242 lines, risk false, api true, skills go-code-review,default-code-review
Triage reasons	a moderate diff reads fine on sonnet
Plugin ref	7a653240672e97f9a61309a09d3617270ce34677
Prompt
Duration	699s (24 turns)
Input tokens (incl. cache)	1082444
Output tokens	17882
Permission denials	22
Total cost	$4.6846
Classifier	off — the comment named a verb, or no arm was usable

[github-actions]

Verdict	Critical/High
REQUEST_CHANGES	2

The diff adds a control-plane column to the API implementations view. The default compact table layout drops the new column, so the fix does not show in default output. A new e2e scenario asserts a JSON field name that the response type does not use, so the assertion fails every run. One test-coverage gap also survived. Additional Risk pass: no secrets, security, or resource-leak issues found in either the Go files or the e2e scenario file.