Bundle 49: secure desktop library import vertical slice

[nulleimy]

Tracking issue for the canonical Bundle 49 boundary repair and merge gate.

• Transaction: applaylist-bundle49-boundary-repair-v1
• Source commit: dd934f875f6f1ce4e73c7fe4a1428e073bbe2c81
• Canonical base: feature/bundle-0-bootstrap @ 2a43f176177fd041f67b90462d06366fb3005415
• Product boundary: secure desktop library import vertical slice
• This Bundle 49 boundary absorbs the unmerged 48B/48C prerequisite scope already embodied in the exact source commit.
• Superseded noncompliant PR boundary: feat(desktop): add secure library import vertical slice #96

Acceptance:

• preserve the exact source commit and 18-file change boundary;
• create a compliant feature/bundle-49-* branch without rewriting history;
• create a compliant Bundle 49 PR with required labels;
• require PR-triggered CI, Desktop Sidecar Proof and PR Guard to pass on the repaired PR;
• do not merge unless every post-repair gate passes;
• do not delete the historical source branch.