fix: resolve 7 code review issues from v0.4.x

- Fix KSUDP clutch field reading fuel at offset 59 (KSUDP has no clutch input)
- Replace Notify with watch::channel for reliable shutdown (no missed wakeups)
- Deduplicate read_u16 from parser_pcars into shared binary_utils
- Remove dead Display impl for FeedSource
- Remove unused read_i8 helper from binary_utils
- Change Vec<Instant> to [Instant; 50] in FeedState (eliminate heap alloc)
- Cache rarely-changing strings by driver_id in Telemetry Tool parser

src/parser_ksudp.rs

@@ -93,7 +93,7 @@ pub fn parse_rt_car_info(data: &[u8]) -> Result<TelemetryFrame, KsudpParseError>
         // Driver inputs
         throttle: read_f32(data, 51),
         brake: read_f32(data, 55),
-        clutch: read_f32(data, 59),
+        clutch: 0.0, // offset 59 is fuel (0.0–1.0), not clutch; KSUDP has no clutch input
         engine_rpm: read_f32(data, 63),
         steer: read_f32(data, 67),