feat(simulation): planet_class temperature envelope, drop orbit/star inputs (T-1033, D-240)

Replace the sun-driven Stefan-Boltzmann temperature with the D-240 class-envelope
model. Temperature derives only from authored fields — no orbit/star physics.

- [planet_class_temperature] envelope table in climate_constants.toml (approved
  bands: frozen [-90,-25] .. hot_arid [20,58] .. volcanic [30,90]); cold_/hot_/
  warm_ prefix parsing; temperate fallback for unknowns.
- derive_temperature_c(params, constants, body_seed): band = envelope(planet_class);
  latitude lerps across it (equator=warm, pole=cold); atmosphere greenhouse +
  elevation lapse modulate within; small seed nudge for per-body variety; CLAMP to
  band — a body can never escape its class. Airless -> None.
- Delete the dead astrophysics: derive_distance_au, ClimateConstants::luminosity(),
  the [star_luminosity] table. Strip orbital_period_days/spectral_class/star_type/
  axial_tilt_deg from BodyParams + BodyParamsReader (read 3 cols from bodies, no
  star_systems join). DB columns left in place (no regen).
- New every_planet_class_derives_within_its_band test (13 classes x 5 atmo x 19 lat
  x 4 seeds, all in band) — the D-240 consistency guard.

Verified on 25 diverse real bodies: the worlds that derived to +356C now sit inside
their class bands (temperate capped at 28C). cargo test passes, clippy -D warnings
clean, fmt clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/data/climate_constants.toml

@@ -1,30 +1,56 @@
-# Climate constants for district temperature derivation (T-1024, D-239 §2).
+# Climate constants for district temperature derivation (T-1024, D-239 §2, D-240).
 #
 # Source-canonical — loaded by the Rust simulation at runtime.
-# These values mirror the tuned constants from tooling/planet-gen/planet_simulation.py.
 # Changing these constants does NOT require a DB migration (runtime file, not DB).
 # To tune: edit here, rerun the server, inspect Atlas temperature maps.
 #
-# Two tables are required:
-#   [greenhouse_offset_c] — mean-annual base temperature offset by atmosphere class.
-#   [diurnal_amplitude_c] — day/night swing AMPLITUDE by atmosphere class.
+# Three tables are required:
+#   [planet_class_temperature]  — per-class [cold_end, warm_end] °C band (D-240).
+#   [greenhouse_offset_c]       — mean-annual base temperature offset by atmosphere class.
+#   [diurnal_amplitude_c]       — day/night swing AMPLITUDE by atmosphere class.
 #
-# Temperature derivation formula (D-239 §2):
-#   T_base = T_stellar_equilibrium + greenhouse_offset_c[atmosphere]
-#   T_mean = T_base + latitude_term + elevation_lapse_term
-#   T_diurnal_amplitude = diurnal_amplitude_c[atmosphere]
+# Temperature derivation formula (D-240):
+#   (cold, warm) = planet_class_temperature[planet_class]    # envelope
+#   t_lat = warm - (warm - cold) * (|latitude_deg| / 90)    # latitude lerp
+#   greenhouse modulates within the band
+#   elevation lapse pulls toward cold end
+#   seed nudge ±~3°C
+#   CLAMP to [cold, warm]  — body can never derive outside its class band.
 #
 # No atmosphere → temperature_c = None (airless body; D-227).
 
+# ---------------------------------------------------------------------------
+# Planet class temperature envelopes (D-240).
+# Each entry: [cold_end_c, warm_end_c] — the band a body of this class stays in.
+# Prefix rules: "cold_*" shifts both ends ~10°C colder; "hot_*" ~10°C warmer;
+# "warm_*" ~5°C warmer. Unknown class falls back to "temperate" band.
+# ---------------------------------------------------------------------------
+[planet_class_temperature]
+frozen        = [-90.0, -25.0]
+ice           = [-90.0, -25.0]
+boreal        = [-35.0,  12.0]
+cold_arid     = [-40.0,  20.0]
+temperate     = [-12.0,  28.0]
+oceanic       = [-12.0,  28.0]
+subtropical   = [  2.0,  34.0]
+warm_ocean    = [  2.0,  34.0]
+tropical      = [ 16.0,  40.0]
+arid          = [ -5.0,  45.0]
+hot_arid      = [ 20.0,  58.0]
+volcanic      = [ 30.0,  90.0]
+geothermal    = [ 30.0,  90.0]
+
 [greenhouse_offset_c]
-# Greenhouse warming contribution per atmosphere class (°C above bare rock).
+# Greenhouse warming contribution per atmosphere class — used as a fractional
+# nudge toward the warm end of the class band, not an absolute Kelvin offset.
 # "none" is not present — airless bodies skip the climate branch entirely (D-227).
-# Values from planet_simulation.py STAR_LUMINOSITY + greenhouse table.
-thin     = 8
-standard = 33
-toxic    = 33  # treated as standard greenhouse for thermal purposes
-breathable = 33  # synonym for standard
-dense    = 80
+# Values represent a 0.0–1.0 fraction of the band width to add toward warm end.
+# thin=0.1 (slightly warmer), breathable/standard=0.25, toxic=0.25, dense=0.55
+thin       = 0.10
+standard   = 0.25
+toxic      = 0.25
+breathable = 0.25
+dense      = 0.55
 
 [diurnal_amplitude_c]
 # Day/night swing amplitude (°C). The actual swing is ±amplitude around the
@@ -39,20 +65,3 @@ standard   = 15   # ~15°C: Earth-like moderate swing
 toxic      = 20   # intermediate: thick but maybe less redistribution
 breathable = 15   # synonym for standard
 dense      = 3    # ~3°C: Venus-like near-uniform temperature
-
-# ---------------------------------------------------------------------------
-# Stellar luminosity lookup (relative to Sol = 1.0).
-# Midpoint per spectral type, matching planet_simulation.py STAR_LUMINOSITY.
-# Used to derive distance_au at runtime from orbital_period_days via Kepler's 3rd law.
-#
-# These values are also used to compute T_stellar_equilibrium:
-#   T_eq_K = 278.5 * (luminosity ^ 0.25) / sqrt(distance_au)
-# ---------------------------------------------------------------------------
-[star_luminosity]
-O = 100000.0
-B = 1000.0
-A = 10.0
-F = 2.5
-G = 1.0
-K = 0.4
-M = 0.04