fix(android): use clipboard paste and verify text entry in input_text

[vishnoorath]

Summary

AndroidAdbDriver.input_text() reported success unconditionally and its clipboard tier was unreachable on local runs, so a text entry that did not land looked identical to one that did. The agent re-typed, saw an unchanged field, and retried indefinitely.

Two concrete defects:

1. Clipboard tier was dead code locally. The tier was gated on if self._ui_adb_client:, but ctx.ui_adb_client is only populated under ARTEMIS_CLOUD_MODE=1 (artemis/drivers/factory.py). On a normal local run it is None, so every entry fell straight through to adb shell input text.

2. Every branch did an unconditional return True. input text failures are silent — the shell call returns without error even when the target app discards the synthesized events. There was no signal that anything went wrong.

Reproduced against a Flutter app (com.nitara.farmer.uat, Android 12), where input keyevent 67 does nothing, so the field could not be cleared either — digits accumulated on every retry.

Changes

• Build a clipboard-capable client lazily via create_screen_client(), so the clipboard tier is live outside cloud mode. It routes through the Artemis Accessibility Helper, whose setClipboard can write the system clipboard on every API level (only reads are restricted since Android 10).
• Prefer clipboard + KEYCODE_PASTE; input text is retained as a fallback.
• Clear through the helper's clear_text RPC when available, instead of 21 synthesized backspaces.
• Verify the entry by reading the focused editable node back and return an honest success/failure, so a silent failure surfaces to the agent instead of looping. Masked password fields and nodes that cannot be inspected stay optimistic.
• Retry once after warming the backend — the first RPC after a cold start can lose the race with the helper attach and spuriously return False.

Verification

On an Android 12 device with a Flutter app, entering a phone number and then a 4-box OTP code now completes in a single pass (13 steps, one run) instead of looping. Both values were confirmed by screenshot: the number field showed the entered value, and a single input_text('1111') call auto-advanced across four separate OTP boxes.

pytest tests/unit/test_drivers.py and the surrounding driver/model-service tests pass (9 passed).

Notes for review

• _verify_focused_text() intentionally stays optimistic when the field cannot be judged — masked fields render dots, and a custom WebView may expose no editable node. The strict check only fires when we can positively see that nothing landed.
• A related bug exists in the Accessibility Helper's findInputNode, which takes the first editable field rather than the focused one, so clear_text can report success while clearing a different field. That needs a Gradle rebuild to ship in the APK and is left out of this change.
• artemis/drivers/android/input_ime.py has a near-duplicate type_text() implementation with no clipboard tier at all. It appears to be unused (no constructor call sites), so it was left untouched to keep this PR scoped to the live path.

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