decoder: broadcast frames to yukart/vehicle/* from contracts' can blocks

Kernel-filtered read-only socket; booleans on change, numbers <= 20/s, every
live value refreshed once a second, stale after 1 s of silence. --replay runs
a candump log through the same path, --list prints the layouts. obd-poller
drops engine_rpm, now a z27ag signal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

src/obd-poller/pids.rs

@@ -16,7 +16,6 @@ fn ab(d: &[u8]) -> f64 {
 }
 
 pub const PIDS: &[Pid] = &[
-    Pid { pid: 0x0C, signal: "engine_rpm", bytes: 2, decode: |d| ab(d) / 4.0, fast: true },
     Pid { pid: 0x0D, signal: "vehicle_speed_kph", bytes: 1, decode: |d| d[0] as f64, fast: true },
     Pid { pid: 0x11, signal: "throttle_pct", bytes: 1, decode: |d| d[0] as f64 * 100.0 / 255.0, fast: true },
     Pid { pid: 0x04, signal: "engine_load_pct", bytes: 1, decode: |d| d[0] as f64 * 100.0 / 255.0, fast: true },
@@ -43,7 +42,6 @@ mod tests {
 
     #[test]
     fn decodes_j1979_examples() {
-        assert_eq!((by(0x0C).decode)(&[0x0D, 0x34]), 845.0); // 0x0D34 / 4
         assert_eq!((by(0x05).decode)(&[0x7B]), 83.0);
         assert_eq!((by(0x10).decode)(&[0x01, 0xF4]), 5.0);
         assert!(((by(0x11).decode)(&[0xFF]) - 100.0).abs() < 1e-9);