Merge displayed bridge-backed range and multi-range read lines into the existing hashline snapshot provenance so INS.POST anchors pass visible-line validation after ACP reads.
Fixes#2773
- Tracked seen-line provenance in snapshots and propagated it from read/search/ast-grep rows.
- Rejected hashline edits on unseen lines before patching, throwing unseen-line errors.
- Rejected single-line block anchors in strict mode and dropped them in unresolved lenient mode.
- Trimmed one-sided keeper-echo duplicates during multi-line replacements with warning output.
roboomp