dorny/paths-filter combines patterns with Array.some, and picomatch compiles
'!.gitea/**' as 'any path not under .gitea'. The '- !.gitea/**' line (from
quick task 260613-dmw) therefore matched every non-.gitea file — including
.planning/** and *.md — so code=true for doc-only PRs and the heavy api/harness
jobs ran anyway. It also never excluded .gitea (the **/*.yml glob already
matched workflow files), regressing the Phase 15 doc-only skip.
Switch to predicate-quantifier 'every' with negation-only globs: a file counts
as code only if it is outside .gitea/, outside .planning/, and not Markdown.
Verified with picomatch against representative file sets.