Make Squad activation summaries report actual label outcomes #1963

Parent: #1957

Blocked by: temporary-ID targeting and fast-path label provisioning under this epic.

Problem

The current activation prose attributes labels to successful create_issue calls. Labels are now applied by separate add_labels safe outputs, so a summary can claim labels that were merely intended or can report a successful run as an omission.

Scope

Align the activation artifact and human-readable summary with the actual label-operation outcomes for both activation paths.

Success criteria

• A label is reported as applied only when the corresponding label operation is accepted successfully for the matching temporary ID or verified issue number.
• Summaries never claim an owner label was carried by create_issue when it was requested through add_labels.
• Failed, skipped, unavailable, multi-owner, and non-roster outcomes remain explicit and distinguishable.
• The Non-roster agent values section appears exactly when required by the established contract.
• Activation bindings remain complete, unique, and tied to the correct task and epic.
• Tests fail when intended labels are reported as actual labels or when successful operations are misreported as omissions.
• Both activation paths use the same reporting semantics.

Out of scope

Changing ownership policy, distributing the post-activation checker, and E4 execution.