v0.5.1

Fixes

CI has been red on every push since v0.5.0 because cargo fmt --check failed
on the first gate, before clippy or tests ever ran. Fixed, and fixing it
surfaced ~50 real pre-existing clippy warnings across tinybridge-core/-cli/
-daemon that clippy had also never gotten a chance to check -- all fixed for
real, not suppressed. Full test suite unchanged and re-verified: 396/396
(excluding daemon) + 185/194 daemon (9 pre-existing named skips).

No functional/behavioral changes in this release -- CI health and code
quality only. See README.md's "Honest status" section for the current,
accurate state of what's verified working vs. not.