Make Rust docs compact visual evidence runnable and publication-blocking

[rmcdaniel]

Problem

The Rust documentation controller now requires source-bound evidence at 640x360, but scripts/pipeline_visual_capture.mjs still rejects heights below 480. The policy schema and workflow therefore advertise and invoke a viewport that the landed capture runtime cannot execute.

This failed the Capture candidate state matrix step for sdk-rust commit 58c735af09600199b12998620cabaa1ecc8ab7f8, skipped source-bound evidence validation, and retained only a failed artifact. The separate Pages publication workflow succeeded, and the later controller landing did not requalify that source revision. A customer-facing visual change can consequently deploy without the evidence the controller says is mandatory.

Acceptance criteria

• Align the capture runtime, policy schema, and workflow so the required 640x360 capture executes successfully.
• Add a regression that invokes the real capture CLI at 640x360; static assertions over workflow text or schema bounds are insufficient.
• Requalify an exact Rust SDK source revision with clean, source-bound 1440x900, 800x900, 390x844, and 640x360 reports and retained screenshots.
• Make Rust documentation publication depend on successful required visual qualification, or provide an equivalent source/controller handshake that prevents publication when a required evidence state cannot run.
• Preserve failure on console, page, HTTP, request, overflow, clipping, control-size, and reachability findings.

Delete when

Delete when a representative Rust documentation UI change cannot publish unless the complete executable visual matrix passes for the exact source revision.

Required source targets

durable-workflow/.github@main
durable-workflow/sdk-rust@main

[rmcdaniel]

Completed in 0421c2e3a78b on main.

Required public qualification Beta candidate (beta-candidate.yml) passed in run 31259555539.

Required cross-repository target qualification passed:

• sdk-rust:main at 77729225659c (qualification)