Keep plant/temp control inert until a Sud is actually loaded

server/brewpi.py no longer pre-configures the real Pot's or Smith's model's
plant params at startup - there's no longer any generic baseline at all,
since the only source of truth is now a loaded Sud's own doc (applied via
tasks/sud.py's SudTask.apply_plant_params(), on Load and on every step).
Ambient temperature and PID gains stay configured at startup, since
they're independent of any Sud (global setting / hardware tuning, not
doc-derived).

Add Pot.is_configured() (already existed)/TempControllerBase.is_configured()/
TempController(Smith).is_configured(), and have tasks/pot.py's PotTask and
tasks/tempctrl.py's TcTask skip process() while not yet configured instead
of letting it raise - so plant and temp control are genuinely inert (not
crashing) until a Sud is loaded. "Normal" has no plant-model dependency,
so it stays active regardless.

Also refreshes README.md: removes stale tracer.py/.mat references (already
removed in an earlier commit), documents SudLogTask's JSON logs, the doc's
L/Td fields, and this inert-until-loaded behavior.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DkkuG48uHFCGKe6dPSERFk

components/pid/temp_controller_base.py

@@ -75,6 +75,14 @@ class TempControllerBase(APid):
 			raise RuntimeError(
 				"{}.process(): PID gains not set - call set_params() first".format(type(self).__name__))
 
+	def is_configured(self):
+		"""Whether set_params() has been called - lets a caller (e.g.
+		TcTask's own process loop) check upfront and skip processing
+		gracefully while not yet configured, rather than relying on
+		process() raising. Overridden by TempController(Smith) to also
+		require its internal model's plant params/ambient."""
+		return self.params is not None
+
 	def on_state_entered(self, state):
 		pass
 

components/pid/temp_controller_smith.py

@@ -32,6 +32,9 @@ class TempController(TempControllerBase):
 		self.model.set_ambient_temperature(theta_amb)
 		self.model_delay.set_ambient_temperature(theta_amb)
 
+	def is_configured(self):
+		return super().is_configured() and self.model.is_configured() and self.model_delay.is_configured()
+
 	def on_state_entered(self, state):
 		if state in (States.HEAT, States.COOL):
 			self.model.initial(self.theta_ist)