Exercise nested Python reference routes in drawer visual qualification

[rmcdaniel]

Problem

The Python documentation visual qualification opens the responsive navigation drawer only on the site root. That fixture is clean, but nested reference pages use translated MkDocs navigation panels with materially different interaction geometry. On the deployed /reference/client/ page at f0a3c6ad02936f131a78bd0f8591b522b49fefd8, open-drawer captures at 768×1024, 390×844, and 640×360 each report three pointer-unreachable controls, while keyboard traversal moves from the close button into occluded logo, repository, Home, and API table-of-contents links. The root-only matrix therefore lets the same defect pass despite enforcing reachability.

Acceptance criteria

• Navigation visual qualification exercises an explicit nested reference route at desktop, intermediate, mobile, and short-height sizes, including the open responsive drawer.
• The gate fails on any non-empty geometry.unreachable_controls result for that state.
• Keyboard evidence traverses the drawer’s active controls and fails if focus enters occluded or translated navigation panels.
• A regression proves the nested fixture fails against the affected behavior and passes only once pointer and keyboard reachability are clean.
• Pull-request and deployment qualification consume the nested-route evidence.

Delete when

Delete when required pre-merge and deployment evidence covers the nested reference drawer at every supported responsive size and cannot pass with occluded controls in either the pointer or keyboard interaction model.

[rmcdaniel]

Completed in 806bc04aac4d on main.

No package release was required for this source-only change.

Required public qualification CI (ci.yml) passed in run 31289837126.