Add SG-Ready startup grace period and daily PV yield tracking

SG-Ready startup grace period (sg_ready_startup_min: 10):
Heat pump compressor takes ~9 minutes to start after receiving the
SG-Ready signal. Previously, idle detection fired after only 3×2min=6min,
turning off SG-Ready before the compressor had time to respond. The grace
period suppresses idle detection for the configured duration after activation.
0 = disabled (tests and unconfigured deployments are unaffected).

Daily PV yield (photovoltaic_production_cumulated_currentDay):
Reads actual kWh produced today from Prometheus (Wh → kWh, ÷1000).
Logged as pv_today_kwh each cycle. Shown on status page in two places:
- PV card sub-line: "Heute: 31.9 kWh"
- Forecast card alongside forecast: "Ist: 31.9 kWh"
Immediately makes forecast vs reality visible (today: forecast 15.9,
actual 31.9 kWh — explains why SOC bypass triggered).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

configs/ems-config.yaml

@@ -15,7 +15,8 @@ prometheus:
     phase_l1_power: "pcc_ac_active_power_phaseOne"             # per-phase grid power L1 (W)
     phase_l2_power: "pcc_ac_active_power_phaseTwo"             # per-phase grid power L2 (W)
     phase_l3_power: "pcc_ac_active_power_phaseThree"           # per-phase grid power L3 (W)
-    ww_top_temp: "heating_dhw_sensors_temperature_dhwCylinder_top_value"  # DHW cylinder top temperature (°C)
+    ww_top_temp: "heating_dhw_sensors_temperature_dhwCylinder_top_value"
+    pv_yield_today: "photovoltaic_production_cumulated_currentDay"  # Wh, converted to kWh by collector (÷1000)  # DHW cylinder top temperature (°C)
 
 # Shelly actuators
 shelly:
@@ -84,6 +85,7 @@ consumers:
   compressor_idle_w: 500      # heat pump compressor below this = idle (W); running starts at ~2700W, so 500W cleanly separates idle (0W) from running
   wallbox_min_charge_w: 50    # wallbox below this = car not charging (W)
   idle_cycles: 3              # consecutive idle cycles before early release (~6 min at 2-min poll)
+  sg_ready_startup_min: 10   # grace period after SG-Ready activation before compressor idle check starts (min)
   wallbox_a_accepted_import_w: 0    # tolerate this much grid import while WallboxA is running (0 = disabled; WallboxA is 2kW, inverter headroom is sufficient)
   wallbox_b_accepted_import_w: 600  # tolerate up to 600W import while WallboxB runs (4kW wallbox + 450W house > 4.6kW inverter max on PV dips)