Mechanism for partial line matches/ignores

**Version and OS**
0.39.17.2 (current) on docker

**Is your feature request related to a problem? Please describe.**
I'm frustrated that the "ignore" matches are for the full line. I want to ignore part of a "line". In the screenshot below I would like to ignore from "Offer ends" onwards, as the date changes and the "View more" wording is added and removed periodically. However, I would still like to trigger a match if the actual "2 for $16" offer changes (eg becomes "3 for $22")

**Describe the solution you'd like**
Ignore lines could be partial matches, with regex allowing people to match on full lines if they choose to, via the use of ".*" and ^/$ beginning/end line position anchors.

**Describe the use-case and give concrete real-world examples**
Per screenshot above, I would like to match on the "2 for $16" text changing, but ignore the date change on the same line.

**Additional context**

The issue does not name implementation files, tests, or entry points. Start by locating the code that applies full-line ignore matches, then trace how line comparisons and regular expressions are handled. Done means an ignore can cover only part of a line while preserving detection of changes in the remaining text, including the stated offer example.

Written by the indexing model from the issue text.