[v0.17 proof] Measure Windows linker time from an explicit boundary

[TheGreenCedar]

Context

Windows package timing in the 0.16.3 release train reported linker evidence from a textual match that also accepted the Rust build line Compiling time v0.3.47. That is the dependency named time, not a linker duration.

The package graph, archive identity, and Windows Vulkan runtime proof all passed. The defect is telemetry-only and was explicitly accepted as a post-release follow-up.

Acceptance

• Measure linker wall time from an explicit timed boundary or structured build trace, not an unscoped substring search.
• Keep cache restoration, Rust compilation, native setup, linking, and packaging as distinct reported intervals.
• A fixture containing only Compiling time v0.3.47 must not satisfy linker-timing evidence.
• A captured real linker invocation/duration must satisfy the selector.
• Timing remains observational; missing timing must not invalidate an otherwise authenticated package.
• Use focused workflow-policy tests and the required hostile mutation. Do not dispatch broad proof from the support PR.

Refs #1611
Refs #1179

v0.17 issue-map role — 2026-08-01\n\nThis issue remains the exact-candidate linker-timing evidence tracker. The workflow/harness source repair is isolated in #1709; its implementation PR closes #1709 only. Do not use #1635 itself as a stack layer.

[TheGreenCedar]

The workflow source repair — replacing the textual linker-time match with an explicit timed boundary or structured build trace while keeping cache restore, compilation, native setup, linking, and packaging as distinct observational intervals — is owned by the open v0.17 package #1709 (WIN-LINK-SRC), coordinated with REL-CI #1670; its implementation PR closes #1709 only. At head the selector is still an unscoped substring count over the whole build stderr (.github/workflows/packaged-platform-proof.yml, MSVC /TIME row grep), so a Compiling time v0.3.47 line can still satisfy it. This issue remains the exact-candidate linker-timing evidence tracker.