Replace granular submodule imports with their parent barrel index
across snapshot diff source and related test files. This covers
util/log, util/filesystem, config/config, provider/provider,
tool/registry, tool/truncate, and the filesystem shared package.
Files over a few thousand lines no longer hang the session for minutes during
summary generation or file view. Diffs for files of any size now render with
full content in the TUI, VS Code sidebar, and web UI — previously they either
froze the event loop or were reported with empty patch text.
Imanol Maiztegui