refactor: Move the ID-or-name resolver out of the task helpers

[DaveHanns]

What

Moves toSafeResourceId, isAmbiguousResourceId, and getResourceByIdOrName from src/tools/tasks/task_helpers.ts to a new module, src/utils/apify_resource_id.ts. No behavior change.

Why

These helpers already resolve tasks, schedules, and Actors, so they don't belong in the task helpers. The source tools (#1453) need the same resolution for their actor argument. The repo lands a refactor before the feature that uses it, so the move comes in its own PR.

Part of #1463.

How

• The new module holds the three functions and the ID regex they use. The code is unchanged. The toSafeResourceId and isAmbiguousResourceId docstrings no longer mention tasks only: they apply to any Apify resource the API addresses by ID or name (Actors, tasks, schedules, ...).
• task_helpers.ts keeps getTaskByIdOrName, the task schemas, the task result shape, and the publication call, and imports the helpers from the new module.
• The task and schedule tools import the helpers from the new module.
• src/tools/AGENTS.md points to the new location.

Testing

type-check, lint, format, test:unit, and check:agents pass. No test imported these functions directly, so no test changed.

AI disclosure: implemented with Claude Code; awaiting human review.

🤖 Generated with Claude Code

[DaveHanns]

Closing: this move is now part of #1453 as its own commit (0d5b6f6), so #1453 and #1454 no longer wait on this PR.