* feat(search_files): path-grouped lossless densification of content matches
Content-mode search_files results repeat the {path,line,content} JSON keys
and the full path string for every match. Group consecutive same-path matches
under one path header with indented '<line>: <content>' rows — lossless (every
path/line/content byte preserved), self-describing (matches_format key), and
readable by the model with no decode step.
57.8% mean token reduction on real search_files content outputs (422-output
corpus), fires on 97% of them. Gated at >=5 matches; below that the verbose
array is left untouched. Default to_dict(densify=False) is unchanged, so no
other caller is affected.
ripgrep emits matches path-ordered, so consecutive grouping never reorders
results.
* test: accept densify kwarg in _FakeSearchResult.to_dict
The search loop-detection tests stub SearchResult with a fake whose
to_dict() must mirror the real signature now that it takes densify=.
* test(search_files): edge-case losslessness battery for densification
Adversarial single-line content (colons, indentation, unicode/emoji, empty,
trailing whitespace, quotes+commas), paths with spaces, and an explicit
one-line-per-match invariant documenting the ripgrep contract the format
relies on (0/6775 real match contents contained a newline).