An explicit path names the project to rebuild; it is not a hint to go
looking for one. resolveProjectPath's upward walk is right for a query run
from a subdirectory, but for a full re-index it silently rebuilt the
nearest initialized parent's graph when <path> had no index of its own.
Refuse with the parent's path and the way to index <path> itself; a bare
`codegraph index` still resolves from cwd as before.
Fixes#1524
Co-authored-by: danusha2345 <ewidusoc498@gmail.com>
