Problem: Combined diffs (`pw > 1`) had no DiffsClear on headers
or `@@@`, no per-char prefix coloring, native TS junk on body
prefixes, and `force_high_priority` flattened all diff captures
to p199 making `@punctuation.special` (cyan) win over
`@diff.minus`/`@diff.plus` (red/green) on `---`/`+++` lines. The
`index` keyword and result hash after `..` were also uncolored.
Solution: Extend `qw > 0` guards to `qw > 0 or pw > 1` for
headers, `@@@`, and body prefixes. Add per-char `@diff.plus` /
`@diff.minus` at p199 on body prefix columns. Apply
`@attribute.diff` on `@@@` lines. Preserve relative priority
offsets in `highlight_treesitter` via `priorities.syntax +
meta_prio - 100`. Add manual `@keyword.diff` and `@constant.diff`
captures on combined `index` lines.
Barrett Ruth
d2921c6fdd