Consolidate config.json.sim into config.json.templ

config.json.templ's component names already default to "sim" for every
backend (sensor/heater/stirrer/plant), making the separate .sim template
mostly redundant - it only differed in dt/sim_warp_factor/PID gain tuning,
which .templ now adopts directly. Removes config.json.sim, updates
brewpi.py's CLI args (-m/--logdir replaces the unused -d/--model/--sim
flags), and refreshes the README/TODO references that pointed at the now-
removed file.

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

config.json.templ

@@ -2,7 +2,7 @@
 	"ambient_temperature": 20,
 	"Controller" : {
 	"dt": 1,
-	"sim_warp_factor": 10.0,
+	"sim_warp_factor": 50.0,
 	"stirrer_name": "sim",
 	"heater_name": "sim",
 	"sensor_name": "sim",
@@ -17,14 +17,14 @@
 			"kt": 0.0
 		},
 		"Heat": {
-			"kp": 0.05,
-			"ki": 0.01,
+			"kp": 0.08,
+			"ki": 0.02,
 			"kd": 0.0,
 			"kt": 1.5
 		},
 		"Cool": {
-			"kp": 0.05,
-			"ki": 0.01,
+			"kp": 0.08,
+			"ki": 0.02,
 			"kd": 0.0,
 			"kt": 1.5
 		},