fix: split inner-loop yi_max clamp to fix HOLD-state windup overshoot

Renames pid_hold/pid_heat/pid_cool to pid_outer/pid_inner/pid_inner_cool
to match what actually runs when, and splits inner-loop config into
Inner.Heat/Inner.Hold/Inner.Cool so the same PID instance gets a tight
yi_max ceiling only while HOLD drives it, without capping legitimate
1.5 K/min ramps. Fixes the overshoot from docs/overshoot_hold_windup.md
where a cold-water disturbance during HOLD wound up pid_heat's integral
term with no anti-windup engagement, taking ~35s+ to unwind naturally.

Breaking config change: Hold/Heat/Cool -> Outer/Inner.{Heat,Hold,Cool}
in config.json, both .tpl templates, the pid/sud demo scripts, and
replay_sim.py's CLI flags. Adds tests/components/pid/ (stdlib unittest)
covering the Pid clamp/recovery behavior and closed-loop disturbance,
ramp, and HOLD<->HEAT transition cases.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DGQhVQ2Y3yXAQTXhrxVd5u

config-sim.json.tpl

@@ -4,23 +4,32 @@
  	"TempCtrl": {
 		"pid_type": "Smith",
 		"beta": 0.05,
-		"Hold": {
+		"Outer": {
 			"kp": 0.4,
 			"ki": 0.0,
 			"kd": 0.0,
 			"kt": 0.0
 		},
-		"Heat": {
-			"kp": 0.08,
-			"ki": 0.02,
-			"kd": 0.0,
-			"kt": 1.5
-		},
-		"Cool": {
-			"kp": 0.08,
-			"ki": 0.02,
-			"kd": 0.0,
-			"kt": 1.5
+		"Inner": {
+			"Heat": {
+				"kp": 0.08,
+				"ki": 0.02,
+				"kd": 0.0,
+				"kt": 1.5
+			},
+			"Hold": {
+				"kp": 0.08,
+				"ki": 0.02,
+				"kd": 0.0,
+				"kt": 1.5,
+				"yi_max": 0.3
+			},
+			"Cool": {
+				"kp": 0.08,
+				"ki": 0.02,
+				"kd": 0.0,
+				"kt": 1.5
+			}
 		},
 		"Thresholds": {
 			"HoldHeat": 1.0,