Partial / manual redaction (select a span to redact)

[prPMDev]

Summary

Let users redact (or protect) a specific span / character range they choose, beyond what automatic detection (patterns + models) finds — e.g. "redact this exact sentence" or "leave that alone."

What already exists

• The engine records per-match character offsets (Change.start / Change.end in ui/src/engine.ts).
• ui/src/pdf-layout.ts (with the spike-pdf.ts / spike.html harness) already proves you can map a [start,end) character span to the exact rectangle(s) on the PDF page. The hard part — span → on-page location — is proven.

What's missing

• A UI to let the user pick the span (select text / drag on the page), then redact just that — reusing the existing modes (fake / mask / label).

Notes

• Tracked in PRD.md under v1.1 (Planned).
• Future work — capturing as a feature request for now.