feat: add -v/-vv verbosity flags and trace-level hex dumps

Add clap CLI argument parsing with three log-level controls:
  -q/--quiet  errors only
  (default)   info — connections and value changes
  -v          debug — every packet's cmd/src/flags logged on TX and RX
  -vv         trace — full 32-byte hex dump of every packet on the wire

RUST_LOG env var continues to work as a fine-grained override for any
of the above levels.

Also expand the TX log line to include src and flags fields to match
the RX line, making the two symmetric.

Cargo.toml

@@ -10,8 +10,9 @@ name = "qmk-host"
 path = "src/main.rs"
 
 [dependencies]
-hidapi   = "2"          # Cross-platform Raw HID access
-anyhow   = "1"          # Ergonomic error handling
-log      = "0.4"        # Logging facade
-env_logger = "0.11"     # Logger implementation (RUST_LOG env var)
-ctrlc    = "3"          # Ctrl+C / SIGINT handler
+hidapi     = "2"         # Cross-platform Raw HID access
+anyhow     = "1"         # Ergonomic error handling
+log        = "0.4"       # Logging facade
+env_logger = "0.11"      # Logger implementation (RUST_LOG env var)
+ctrlc      = "3"         # Ctrl+C / SIGINT handler
+clap       = { version = "4", features = ["derive"] }  # CLI argument parsing