fix(VAutocomplete): use hidden select for native form submissions

[faizkhairi]

Description

Apply the same fix pattern from VSelect (#22330) to VAutocomplete. When using v-model or :model-value, the component's input value was empty until user interaction, breaking native form submission and Cypress tests.

Root Cause

VAutocomplete uses a real <input> for its search field, but the input's value is only populated when the component is focused (isFocused watcher sets search.value). This means native form submission always submits an empty string.

Fix

Mirror the VSelect fix from #22330:

1. Import and call useAutocomplete(props) — reuses the existing composable created in fix(VSelect): Use hidden select for native form submissions #22330
2. Pass name={undefined} to <VTextField> — excludes the visible text input from form submission
3. Render a hidden <select> with <option> elements driven by items and selectedValues — this is what native form submission reads

Tests Added

• Single selection: verifies FormData contains the selected value
• Multiple selection: verifies FormData contains all selected values

Related

• Fixes [Bug Report][3.10.7] VAutocomplete's input value #22270
• Follows the same pattern as fix(VSelect): Use hidden select for native form submissions #22330 (VSelect)
• As suggested by @J-Sek in [Bug Report][3.10.7] VAutocomplete's input value #22270 comment

AI Disclosure

This contribution used AI assistance (Claude Code) for codebase exploration and implementation.