Add explicit initial grain_mass/water_mass to the Sud doc

Sud now parses top-level grain_mass/water_mass (sibling to pot_mass/
pot_material/L/Td, defaulting to 0/0) - what's actually in the pot before
the brew starts, as opposed to default.step's grain_mass/water_mass, which
is just inert template filler. All sude/*.json docs gain explicit values
matching what their first step already resolved to.

tasks/sud.py's apply_plant_params() now takes grain_mass/water_mass
directly instead of a step dict: on_step_changed() still passes the active
step's own (these vary as malt goes in/water boils off), but the Load
handler now reads Sud.grain_mass/water_mass directly instead of parsing
schedule[0]. The GUI's status-line mass preview (shown immediately on
Load, before Start) does the same.

Also fixes a latent bug found along the way: _continue_forecast_after_confirm()'s
reconstructed sub-doc was missing L/Td/grain_mass/water_mass entirely,
silently falling back to generic defaults instead of the real Sud's own
values - invisible only because every current sude/*.json happens to use
those same defaults.

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

tasks/sud.py

@@ -55,17 +55,20 @@ class SudTask(ATask):
 		self.forecast_confirm_marks = {}
 		msg_handler.set_recv_handler(self.recv)
 
-	def apply_plant_params(self, step):
+	def apply_plant_params(self, grain_mass, water_mass):
 		"""Keeps the real plant's and the controller's internal model's
 		plant params in sync with this Sud's own doc - L/Td come straight
 		from it (constant for the whole brew), while M/C also fold in the
-		step's grain_mass/water_mass, which vary over the brew's course
+		given grain_mass/water_mass, which vary over the brew's course
 		(malt going in, water boiling off) - mirrors demo_sud.py's
 		apply_plant_params(). Called both on every real step transition
-		(via on_step_changed()) and once immediately on Load (see recv()),
-		so the controller's behavior already matches the expected plant
-		as soon as a Sud is loaded, not just once a run actually starts."""
-		params = self.sud.derive_plant_params(step.get('grain_mass', 0), step.get('water_mass', 0))
+		(via on_step_changed(), with that step's own grain_mass/water_mass)
+		and once immediately on Load (see recv(), with the doc's own
+		initial Sud.grain_mass/water_mass - no need to parse the first
+		step out of the schedule for that), so the controller's behavior
+		already matches the expected plant as soon as a Sud is loaded,
+		not just once a run actually starts."""
+		params = self.sud.derive_plant_params(grain_mass, water_mass)
 		self.pot.set_plant_params(params)
 		if hasattr(self.tc, 'set_model_plant_params'):
 			self.tc.set_model_plant_params(params)
@@ -95,7 +98,7 @@ class SudTask(ATask):
 		phase = ramp if ramping else hold
 
 		if step is not None:
-			self.apply_plant_params(step)
+			self.apply_plant_params(step.get('grain_mass', 0), step.get('water_mass', 0))
 			if ramping and step['temperature'] is not None:
 				self.tc.set_theta_soll(step['temperature'])
 				self.tc.set_heatrate_soll(ramp['rate'])
@@ -214,6 +217,10 @@ class SudTask(ATask):
 			'Description': self.sud.description,
 			'pot_mass': self.sud.pot_mass,
 			'pot_material': self.sud.pot_material,
+			'L': self.sud.L,
+			'Td': self.sud.Td,
+			'grain_mass': self.sud.grain_mass,
+			'water_mass': self.sud.water_mass,
 			'steps': schedule[index:],
 		}
 		start_theta = self.tc.get_theta_ist()
@@ -264,12 +271,12 @@ class SudTask(ATask):
 					# on_step_changed() only re-applies plant params once a
 					# real step starts (Start) - apply them right away too,
 					# so the controller already matches this Sud's own pot/
-					# L/Td (and its first step's expected grain/water mass)
-					# from the moment it's loaded, rather than whatever the
-					# previously loaded Sud (or the generic startup
-					# baseline - see server/brewpi.py) left behind.
+					# L/Td/initial grain_mass/water_mass from the moment
+					# it's loaded, rather than whatever the previously
+					# loaded Sud (or the generic startup baseline - see
+					# server/brewpi.py) left behind.
 					if self.sud.schedule:
-						self.apply_plant_params(self.sud.schedule[0])
+						self.apply_plant_params(self.sud.grain_mass, self.sud.water_mass)
 					await self.send_forecast(pair[1])
 				else:
 					# Sud.load() refuses while a run is in progress (state