[feat]: Create `<pf-v6-time-picker>` element

[bennypowers]

Summary

Create a <pf-v6-time-picker> web component implementing the PatternFly v6 Time picker component.

Time selection input with dropdown suggestions for 12-hour and 24-hour formats.

Prior Art

Source	Element	Status
PFE v4	--	--
cem	--	--
cockpit	--	--
chickadee	--	--

Requirements

• MUST implement PFv6 visual designs
• MUST provide end-user feature parity with @patternfly/react-core TimePicker
• MAY adjust element API to leverage web platform strengths
• SHOULD maintain CSS custom property theming compatibility
• SHOULD expose useful CSS shadow parts

Element-specific considerations

• FACE: formAssociated = true, ElementInternals - submits time string value
• time / value prop (string, e.g. "2:00 AM" or "14:00")
• is24Hour prop for format toggle
• stepMinutes for dropdown suggestion interval (default 30)
• minTime / maxTime to restrict valid range
• placeholder for input hint text
• Text input with typed entry + time suggestions dropdown (combobox pattern)
• Combobox: role="combobox", aria-expanded, aria-controls pointing to listbox
• Listbox: role="listbox", options role="option", aria-selected
• Floating UI for dropdown positioning (consider pf-v6-select as model)
• Validation: parse typed time, check against min/max, set aria-invalid
• Keyboard: Arrow down opens suggestions, Arrow up/down navigates, Enter selects, Escape closes

Checklist

Implementation

• formAssociated = true
• ElementInternals for value/validity reporting
• API per .claude/ADVICE.md
• CSS uses v6 tokens, logical properties, nesting
• @summary and JSDoc on element class

Demos

• Demos match patternfly.org naming/structure
• CSS custom properties match computed styles from patternfly.org (Chrome MCP)
• Visual parity verified via Chrome MCP

Tests

• Public API covered (attributes, properties, events, slots)
• a11ySnapshot assertions
• Form submission test

Reviews

• /review-api passes
• /review-demos passes
• /review-a11y passes
• eslint and stylelint pass

Ship

• Add changeset
• PR targets staging/pfv6 (NOT main)