Historically every bin (claw-store, claw-cargo, claw-fuse)
re-declared the same 13-line 'mod ...' block at its own root.
Working but fragile — a new bin (or a new module) needed edits
in N+1 places and stayed one edit-slip away from silently
dropping something.
Now: src/lib.rs owns the shared module tree. Cargo.toml gets a
[lib] entry so cargo picks it up. claw_fuse.rs migrated as the
proof-of-concept — 13 mod lines → 4 use lines.
claw-store + claw-cargo bins still use their internal 'mod ...'
blocks and 'crate::...' paths — migrating them is mechanical
but noisy; deferred to a follow-on so this PR stays reviewable.
Both bins + tests continue to build unchanged.
387 tests pass.