Add validate-browser-scenario for offline schema and semantic checks of inline JSON, local files and stdin. Return compact validity/action/secret counts without reading secret values or discovering, launching, attaching to or navigating a browser.
Execution and validation share CLI input admission and the canonical domain schema. Preserve existing capture lifecycle, diagnostics, cancellation and caller-relative executable paths.
Integrates #7149 with attribution. Fixes#5488. Validation includes 24 focused tests, static/build/docs checks, and the preserved real PocketBase scenario with its backend stopped and secret variables unset. Verification and resource/token measurements are recorded in docs/verification/browser-scenario-validation-2026-10-27.md.
Co-authored-by: Ace <1160684883@qq.com>