[coneilen]

Summary

Adds the fifth Windows onboarding page, “One window per line of work,” before backend selection so the tour matches the macOS page order without changing existing first-run persistence or backend behavior.

Changes

• draw the workspace lesson with native GDI components and five progress indicators
• move backend hit testing, keyboard focus and UIA actions from page 4 to page 5
• extend the scrubbed first-run contract to advance through five pages
• preserve existing onboarding-seen markers and record the remaining visual/input evidence limits in the parity ledger

Test plan

RED: zig test src\WindowsOnboarding.zig --test-filter "five-page macOS contract" -> 1/1 executed; expected 5, found 4
GREEN: zig test src\WindowsOnboarding.zig --test-filter "five-page macOS contract" -> All 1 tests passed
REGRESSION: zig test src\WindowsOnboarding.zig -> All 16 tests passed

Additional focused result: zig test src\WindowsOnboarding.zig --test-filter "workspace" -> All 3 tests passed.

Not verified locally:

• native product build and C++ provider linkage
• ScrubbedShellStartup.Live.Tests.ps1 execution with built shell/daemon/CLI artifacts
• paired macOS/Windows screenshots or raster fidelity
• physical keyboard operation or screen-reader behavior
• broad Windows validation; exact-head CI owns broader regression

Checklist

• I have read the Contributing Guidelines
• I have signed off my commits (git commit -s) per the DCO
• Tests pass locally (make test)
• Code follows the existing style (make check)
• I added the test/contract before the implementation and observed the intended RED failure