* fix: add appium: vendor prefix to iOS capabilities for Appium v3
Appium v3 enforces the W3C WebDriver spec strictly, requiring
non-standard capabilities to use vendor prefixes. The iOS provider
was sending capabilities like `automationName`, `noReset`, `deviceName`,
`platformVersion`, and `udid` without the required `appium:` prefix,
causing session creation to fail with InvalidArgumentError.
This change prefixes all non-standard capabilities with `appium:` while
leaving standard W3C capabilities (`platformName`, `browserName`)
unprefixed. Backwards-compatible with Appium v2, which accepts both
formats.
Fixes#629
* fix: extract build_ios_capabilities for testable production code path
Addresses review feedback: removes unused `mut manager` warning and
validates the actual capability-building logic instead of reconstructing
JSON inline.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---------
Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
