fix(frontend): focus rings are near-invisible and ramp-option radios are keyboard-unreachable #750

Summary

Keyboard focus indicators are effectively invisible or removed in several components, and the plan ramp-option radios are display:none, so those cards cannot be reached by keyboard.

Where

Reviewed commit b50ca38.

• frontend/src/styles/forms.css:104-108 (chips and chip-select: outline:none; box-shadow:0 0 0 3px var(--cudly-info-bg), a #eff6ff halo at about 1.07-1.09:1 on white)
• frontend/src/styles/components.css:948 (.rec-cell-chevron:focus-visible{outline:none}, no border either), :1527-1528, :1588-1589
• frontend/src/styles/forms.css:289 and frontend/src/styles/plans.css:195 (.ramp-option input[type=radio]{display:none})

Failure scenario

A keyboard user tabbing through filters, chip selects and the recommendation chevrons cannot see where focus is (the only cue is a 1px border colour change). In the plan editor, the ramp-option radios are removed from the tab order, so the plan cards cannot be chosen without a mouse. WCAG 2.4.7 and 2.1.1. Verification level: source-level; the contrast ratio is computed from the CSS values, not measured in a browser.

User impact

Keyboard-only and low-vision users cannot track focus in core controls or pick a ramp option.

Suggested fix

Define --cudly-focus-ring: 0 0 0 2px var(--cudly-surface), 0 0 0 4px var(--cudly-primary) and a global :where(button,a,input,select,textarea,[tabindex]):focus-visible rule using it; replace display:none on the radios with a visually hidden (.sr-only) pattern and style the card with :has(input:focus-visible).

Related: #191 (polish backlog; one checkbox asks to "verify" keyboard access and focus states, the measured failures here are new).

Screenshots

usab-plans.png (in the review fleet archive at /Users/cristi/.claude/agent-comms/review-fleet-20261008/screens/, NOT uploaded).

Severity

Medium: affects all keyboard users across several controls, and blocks one selection UI entirely.

Reviewer ID: UX-26 (vis M4 + usab L12)
Found by the 2026-10-08 review fleet.