[FEAT] Add InjectionHandle wait_until_ready hook

[Nina Chikanov (nina-msft)]

Today, the only mechanism to wait for injected content to become visible to the target agent is a fixed asyncio.sleep() driven by InjectionHandle.indexing_delay_seconds (see XPIAExecution._activate_handles_async()). This works for simple time-based delays but doesn't generalize to scenarios where readiness can be actively verified, such as:

• Polling an API until an injected document appears in search results
• Querying a database row until it becomes visible
• Waiting for a webhook callback or pipeline completion

This PR introduces a wait_until_ready async method on the InjectionHandle protocol that surfaces can override to implement custom readiness logic. The current sleep-based delay becomes one default implementation of this hook.

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Protocol Changes (Breaking)

• Removed indexing_delay_seconds property from InjectionHandle protocol.
• Added wait_until_ready() async method to InjectionHandle protocol — surfaces now control their own readiness strategy instead of exposing a passive delay value.

New

• sleep_until_ready(delay) — free helper function in rampart.core.injection for surfaces that only need a simple sleep-based readiness wait.
• _OneDriveInjection.wait_until_ready() — delegates to sleep_until_ready using the surface's indexing_delay. Future versions will poll the Graph API instead.
• TestOneDriveInjectionWaitUntilReady — test class verifying the OneDrive wiring to sleep_until_ready.

Changed

• XPIAExecution._activate_handles_async — replaced sequential max(indexing_delay_seconds) + asyncio.sleep with concurrent per-handle readiness via asyncio.TaskGroup.
• OneDriveSurface — internal references changed from private attributes (self._drive_id, self._folder_path) to public property accessors (self.drive_id, self.folder_path).
• test_xpia.py — _mock_handle no longer sets delay / indexing_delay_seconds; cleanup tests now assert wait_until_ready was called.
• test_protocols.py — structural subtyping tests updated to match the new protocol shape.
• test_onedrive.py — assertions use public properties; removed test_indexing_delay_from_surface.

Housekeeping

• Fixed unnecessary f-string prefixes on strings without interpolation in onedrive.py.
• Removed !.vscode/settings.json from .gitignore.

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• unit tests pass
• pre-commit run --all-files run w/ success

[Bashir Partovi (bashirpartovi)]

Looks great