Extracts rg and git-grep search logic into src/shared/text-search.ts so
the local main and SSH relay paths stop reinventing arg construction,
JSON parsing, submatch regex, and accumulator/truncation semantics.
Fixes silent truncation in the relay: searchWithRg used execFile with
a 50MB maxBuffer cap that rg --json easily exceeds on large repos,
dropping matches with no error surfaced to the user. The relay now
streams via spawn, matching the local path.
See docs/design/share-text-search.md for full rationale.
Co-authored-by: Orca <help@stably.ai>
099c4089a7