fix(app): clarify driver activation feedback

[gly11]

Summary

This PR is stacked on pr/app-sbp2-device-metadata and improves normal app feedback around driver activation while keeping a small metrics timer cleanup with it.

Driver Activation Feedback

• Report bundle scan and system extension submission failures with clearer errors
• Make activation status text selectable for troubleshooting
• Avoid holding a strong self reference from the metrics refresh timer

Why this PR

These are app polish fixes that are useful on their own and should not be bundled with local diagnostic or install-helper work. Keeping this slice separate makes the user-facing activation behavior easy to review.

This PR intentionally does not include debug UI, diagnostic handlers, local scripts, install helpers, or documentation-only planning notes.

Verification

Local verification completed for this slice:

git diff --check pr/app-sbp2-device-metadata..HEAD
xcodebuild -project ASFW.xcodeproj -scheme ASFW -configuration Debug -destination 'platform=macOS' CODE_SIGNING_ALLOWED=NO build
xcodebuild -project ASFW.xcodeproj -scheme ASFW -configuration Debug -destination 'platform=macOS' CODE_SIGNING_ALLOWED=NO test