Fix nextCommandHint for empty JSON plans

[k-o-c-o]

What changed

• Updated nextCommandHint to prioritize the analysis/explain hint for weak plans.
• Prevented the JSON verify hint from being shown when contextFiles is empty.
• Added a regression test to verify that empty JSON plans display the analysis hint instead of the verify hint.

Why

When a JSON plan contains no context files, the CLI still suggested running fixmap verify, even though there was nothing useful to verify. This could mislead users and hide the more helpful analysis/explain guidance. This change ensures the analysis hint is shown first for weak or empty plans.

Verification

• npm run ci
• New or changed behavior has focused tests
• Generated Action bundle is committed when Action source changed

FixMap receipt

• Built packages/core and packages/cli.
• Ran npm test in packages/cli and confirmed all tests passed, including the new regression test for empty JSON plans.
• Did not run the full npm run ci.