Listings now filter both '.' and '_' prefixes:
- '.' entries: excluded from listings AND 404 on direct HTTP access
(existing behavior). For invisible side-state like .devshell.
- '_' entries: excluded from listings only — direct URL access still
works. For operator scaffolding like install.zip's _template/
directory of bootstrap stubs that should be reachable but should
not appear in the project picker.
Filter applied at both listing entry points: ServeProjectList (the
project picker JSON at GET / Accept: application/json) and the generic
listing/FromDirEntries (used by ServeDirectory for sub-directory
browse listings).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
