fix(cli): reject unlinked umbrella blockers

[lafawnduh1966]

Summary

Implements BRIX-1537 by making same-umbrella dependencies follow the same V1 rule as normal Linear dependencies: incomplete blockers must resolve to an existing Quay task before the dependent subtask can be enqueued.

Behavior

• If a same-umbrella blocker is linked to a Quay task, enqueue still creates an umbrella-scoped dependency requiring merged_to_feature_branch.
• If a same-umbrella blocker is complete in Linear and not linked to Quay, enqueue still treats it as complete outside Quay and does not persist a dependency row.
• If a same-umbrella blocker is incomplete and not linked to Quay, enqueue now fails with dependency_not_tracked before task/worktree/artifact/dependency side effects.
• The error details include the blocker ref, repo, umbrella parent ref, and umbrella workflow id.

Spec Check

This matches the spec requirement that incomplete Linear blockers resolve to existing Quay tasks and that V1 must not create unresolved dependency rows.

Tests

• bun test packages/cli/tests/cli/enqueue_linear_issue.test.ts
• bun test packages/cli/tests/core/task_dependencies.test.ts packages/cli/tests/tick/tick_001_promotes_queued_to_running.test.ts packages/cli/tests/pr/test_053_pr_open_merged_transitions_terminal.test.ts
• bun run scripts/embed.ts
• bun run typecheck:cli

[linear]

BRIX-1537

[lafawnduh1966]

lgtm!