Model capacitor banks (series for voltage, parallel for current/capacitance)

Per user: each stage's energy source is now a bank of real capacitors,
n_series x n_parallel, not a single cap.

- components/schema.py CapacitorBank.from_spec: series multiplies voltage
  and ESR and divides capacitance; parallel multiplies capacitance and
  max current and divides ESR; price and count scale with total cap count.
  Duck-typed as a drop-in for CapacitorSpec in StageConfig.
- search_space: cap_series (1-6) and cap_parallel (1-8) per stage gene,
  sampled/mutated/repaired; decode builds the bank; charge voltage capped
  by min(bank voltage, switch rating)
- objective.build_detail records the full bank composition (base part,
  series/parallel, count, totals) and current-capability diagnostics:
  bank_current_over_limit / switch_current_over_limit vs peak discharge
  current (a warning, not a hard reject -- DB holds datasheet not pulse
  ratings; parallel caps already help for real via lower ESR)
- BOM shows "N шт (Sпосл × Pпар)" with per-unit and total price

Already supported and confirmed present (also user-requested): per-coil
independent wire gauge (wire_idx per stage) and computed wire length
(winding_geometry.total_wire_length_m, drives resistance/cost/DB detail).

83 tests pass.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_capacitor_bank.py

@@ -0,0 +1,80 @@
+import random
+
+import pytest
+
+from gausse.components.database import ComponentDatabase
+from gausse.components.schema import CapacitorBank, CapacitorSpec
+from gausse.optim.objective import build_detail
+from gausse.optim.search_space import SearchBounds, decode, sample_genome
+from gausse.sim.coilgun import run_coilgun
+
+BASE = CapacitorSpec(
+    part_number="c-base", capacitance_uf=100.0, voltage_v=400.0, esr_ohm=0.2,
+    max_current_a=20.0, price=150.0, source="test",
+)
+
+
+def test_series_multiplies_voltage_and_divides_capacitance():
+    bank = CapacitorBank.from_spec(BASE, n_series=3, n_parallel=1)
+    assert bank.voltage_v == pytest.approx(1200.0)          # 400 * 3
+    assert bank.capacitance_uf == pytest.approx(100.0 / 3)  # C / 3
+    assert bank.esr_ohm == pytest.approx(0.6)               # ESR * 3
+    assert bank.count == 3
+    assert bank.price == pytest.approx(450.0)               # 150 * 3
+
+
+def test_parallel_multiplies_capacitance_current_and_divides_esr():
+    bank = CapacitorBank.from_spec(BASE, n_series=1, n_parallel=4)
+    assert bank.capacitance_uf == pytest.approx(400.0)      # C * 4
+    assert bank.voltage_v == pytest.approx(400.0)           # без изменения
+    assert bank.esr_ohm == pytest.approx(0.05)              # ESR / 4
+    assert bank.max_current_a == pytest.approx(80.0)        # 20 * 4 -- вот "на силу тока"
+    assert bank.count == 4
+
+
+def test_series_parallel_combination():
+    bank = CapacitorBank.from_spec(BASE, n_series=2, n_parallel=3)
+    assert bank.voltage_v == pytest.approx(800.0)
+    assert bank.capacitance_uf == pytest.approx(100.0 * 3 / 2)
+    assert bank.esr_ohm == pytest.approx(0.2 * 2 / 3)
+    assert bank.count == 6
+    assert bank.price == pytest.approx(150.0 * 6)
+
+
+def test_energy_scales_with_bank():
+    single = CapacitorBank.from_spec(BASE, 1, 1)
+    bank = CapacitorBank.from_spec(BASE, 2, 2)  # V×2, C×1 (2 series, 2 parallel => C*2/2=C)
+    e_single = 0.5 * (single.capacitance_uf * 1e-6) * single.voltage_v**2
+    e_bank = 0.5 * (bank.capacitance_uf * 1e-6) * bank.voltage_v**2
+    # тот же C, но вдвое большее напряжение -> вчетверо больше энергии
+    assert e_bank == pytest.approx(4 * e_single)
+
+
+def test_decoded_record_contains_capacitor_bank_composition():
+    db = ComponentDatabase.load()
+    bounds = SearchBounds()
+    rng = random.Random(1)
+    genome = sample_genome(db, bounds, rng)
+    config, ix, iv = decode(genome, db, bounds)
+    result = run_coilgun(config)
+    detail = build_detail(config, result, db, ix, iv)
+    bank = detail["stages"][0]["capacitor_bank"]
+    assert set(bank) >= {"base_part", "n_series", "n_parallel", "count", "total_voltage_rating_v", "max_current_a"}
+    assert bank["count"] == bank["n_series"] * bank["n_parallel"]
+    # база должна быть реальной деталью
+    assert bank["base_part"] in {c.part_number for c in db.capacitors}
+
+
+def test_genome_carries_series_parallel_and_they_vary():
+    db = ComponentDatabase.load()
+    bounds = SearchBounds()
+    rng = random.Random(5)
+    series_vals, parallel_vals = set(), set()
+    for _ in range(40):
+        g = sample_genome(db, bounds, rng)
+        for st in g.stages:
+            assert bounds.cap_series_min <= st.cap_series <= bounds.cap_series_max
+            assert bounds.cap_parallel_min <= st.cap_parallel <= bounds.cap_parallel_max
+            series_vals.add(st.cap_series)
+            parallel_vals.add(st.cap_parallel)
+    assert len(series_vals) > 1 and len(parallel_vals) > 1