fix(jobs): correct config-hint path and honor --dry-run on curated commands

[ClayMav]

Summary

Two independent bugs surfaced while smoke-testing the BYOC runtime/region default rollout in PR #26. Neither was caught by CI because both fail silently.

BUG 1 — completion lookups used the wrong API path

internal/commands/jobs.go looked up /notebooks/config-hint for the --runtime/--run-region tab-completion. The actual studio-backend endpoint is /me/jupyter/lab/config-hint. findOperation returned nil, so completeConfigHint returned an empty slice — completion failed open and tab-completion silently produced no suggestions.

BUG 2 — curated job-runs create (and siblings) ignored --dry-run

The global --dry-run flag (registered in builder.go) was honored only by dynamic API commands. Curated job-runs create/list/logs/metrics called execOnce/execWithRetry directly, so wherobots job-runs create ... --dry-run would actually submit a job (confirmed empirically on staging).

The fix introduces a small executeOrDryRun helper on jobsRunner that prints the curl equivalent and returns (nil, nil) when --dry-run is set. All four curated entry points (create, logs, list, metrics) now route their primary request through it and short-circuit on nil respBody. For create specifically, prepareScript (org lookup + presigned-URL upload) is also skipped so dry-run produces no side effects at all.

Test plan

• go test ./... passes.
• TestJobsCompletionUsesConfigHintPath — asserts __complete job-runs create ... --run-region "" hits /me/jupyter/lab/config-hint and emits the seeded regions.
• TestJobsCreateDryRunSkipsRequest — asserts job-runs create ... --dry-run issues zero HTTP requests and emits the expected curl -X POST '…/runs' line.
• TestJobsListDryRunSkipsRequest — same shape for the read-only list path.
• Manual smoke test on staging:
  • WHEROBOTS_API_URL=…staging… ./bin/wherobots __complete job-runs create s3://x.py --name x --run-region "" returns the four org regions + completion directive 4.
  • WHEROBOTS_API_URL=…staging… ./bin/wherobots job-runs create s3://fake-bucket/x.py --name dryrun-test --dry-run -y prints a curl line and creates no run.