docs: cover readiness, verification, and recursive discovery

[djgormley]

The public guide omits doctor and verify from its navigation and command overview, while recursive discovery and several other current features are difficult to find.

Add practical guides for readiness checks, verification, and recursive discovery. Link every command from the overview, organize the User Guide around setup, discovery, downloads, troubleshooting, and JSON output, and connect inventory creation to resumable manifest downloads. Correct the certificate setting in the setup examples to vospace_certfile and add a post-setup doctor check.

Validation: strict standalone MkDocs build; all 18 generated pages and 869 internal references/search targets; overview links for all 12 registered commands; focused pre-commit hooks; source review and browser checks of the new guides. No runtime behavior changes.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.99%. Comparing base (f52a917) to head (565a685).
⚠️ Report is 74 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #201       +/-   ##
===========================================
+ Coverage   67.08%   82.99%   +15.91%     
===========================================
  Files          16       33       +17     
  Lines        1686     4493     +2807     
===========================================
+ Hits         1131     3729     +2598     
- Misses        555      764      +209     

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