chore: Remove deprecated get-actor-output tool

[jirispilka]

Problem

get-actor-output was deprecated in #814 — description prefixed DEPRECATED:, removed from auto-injection. Kept in the storage category for one minor cycle so existing sessions/configs don't break on upgrade.

This issue tracks the full removal in the next minor cycle.

Proposed solution

After #814 ships in a release:

1. Delete src/tools/common/get_actor_output.ts.
2. Remove getActorOutput from src/tools/categories.ts (storage array + import).
3. Remove HelperTools.ACTOR_OUTPUT_GET constant.
4. Drop integration tests that exercise the tool (currently around tests/integration/suite.ts:2030, 2076, 2138 — verify line numbers at the time).
5. Remove the tool from any x402 / Skyfire allowlists.
6. Coordinate with apify-mcp-server-internal — verify no internal caller imports getActorOutput directly.

Callers should use get-dataset-items. Behavioral differences vs get-actor-output (see #814 PR body for migration notes):

• get-dataset-items does not default clean: true
• get-dataset-items does not strip empty properties or truncate output
• get-dataset-items flattens server-side from dot-notation fields (no local projection)
• Different default limit (20 vs 100)