Add verification-only retries and resumable pauses to plan execution

[DevMando]

Desktop previously treated an unavailable verification response like a failed implementation step. Choosing retry could repeat code changes, and pauses or checkpoint problems were not clearly explained.

This change gives users recovery options that match what actually failed and integrates the shared planner fixes from DevMando/MandoCode#87.

What changes for users

• When verification is unavailable, users can choose Retry verification or Pause plan. Retrying checks the saved evidence without rerunning implementation.
• Progress messages distinguish execution, targeted repair, and verification.
• Paused plans and checkpoint-saving problems are shown explicitly, including when resuming an unfinished plan.
• The MandoCode dependency is updated to include the hang fixes, preserved evidence, bounded verification retries, and recovery safeguards.

Validation

• 243 Desktop tests passed during integration validation.
• 143 shared-planner tests passed on both .NET 8 and .NET 10 after the final evidence-retention change.
• Desktop built successfully in an isolated output folder with zero warnings or errors. The running Desktop/Visual Studio session locked the normal output DLL.
• The latest user acceptance session completed all four steps. A retry strengthened runtime checks and led to fixes for real ghost movement and restart defects.

Review and merge order

Merge DevMando/MandoCode#87 first, then this PR. This PR references shared-planner commit 1f7a7ec. If the shared PR is squash-merged or rebased, update the dependency reference here to the resulting commit on main before merging.

Overlapping steps and inconsistent model interpretation of acceptance criteria remain follow-up work. Successful headless checks do not establish complete real-browser behavior.