Módulo 1: visores 2D del plano de líneas + hidrostáticos en vivo

- viewer_lines.py: BodyPlanViewer, ProfileViewer, PlanViewer (QPainter,
  zoom/paneo, tema dark navy); conectados a los tres viewports 2D del
  layout 4-viewport (bodyplan / profile / plan).

- hull.py: añadidos waterplane_coefficient (Cw), it_waterplane (IT),
  il_waterplane (IL), bm_transverse (BMT), bm_longitudinal (BML),
  km_transverse (KMT), tpc, mct1cm — todos verificados analíticamente
  contra el casco Wigley (IACS Rec.34 §4.3).

- main_window.py: _load_hull_viewers() conecta los 4 visores y el panel
  hidrostáticos al crear un nuevo proyecto; _update_hydrostatics() puebla
  los 11 campos de la barra inferior en vivo.

- test_module1_hydrostatics.py: 35 tests nuevos (IT analítico exacto,
  consistencia BMT=IT/V, KMT=KB+BMT, TPC=Awp·ρ/1e5, visores headless).

Suite total: 86 tests — 86 passed.

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

arshipdesign/core/hull.py

@@ -237,6 +237,102 @@ class Hull:
         V = self.volume_of_displacement(draft)
         return V * rho / 1000.0
 
+    def waterplane_coefficient(self, draft: Optional[float] = None) -> float:
+        """Coeficiente de plano de flotación Cw = Awp / (Lpp · B).
+
+        IACS Rec.34 §3.3 — parámetro adimensional de la forma del plano de flotación.
+        """
+        T = draft if draft is not None else self.draft
+        awp = self.waterplane_area(T)
+        return awp / (self.lpp * self.beam)
+
+    def it_waterplane(self, draft: Optional[float] = None) -> float:
+        """Segundo momento de área del plano de flotación sobre el eje de crujía IT [m⁴].
+
+        IT = (2/3) · ∫₀^L y(x,T)³ dx
+
+        Rawson & Tupper, "Basic Ship Theory" 5ª ed., Cap. 3.
+        """
+        T = draft if draft is not None else self.draft
+        x = self.offsets.x_stations
+        y_wl = np.array([self.offsets.half_breadth(xi, T) for xi in x])
+        integrand = (2.0 / 3.0) * y_wl ** 3
+        if len(x) >= 3:
+            return abs(float(simpson(integrand, x=x)))
+        return abs(float(np.trapz(integrand, x)))
+
+    def il_waterplane(self, draft: Optional[float] = None) -> float:
+        """Segundo momento de área del plano de flotación sobre el centro de flotación IL [m⁴].
+
+        IL = ∫₀^L (x − LCF)² · 2y(x,T) dx
+
+        Rawson & Tupper, "Basic Ship Theory" 5ª ed., Cap. 3.
+        """
+        T = draft if draft is not None else self.draft
+        x = self.offsets.x_stations
+        y_wl = np.array([self.offsets.half_breadth(xi, T) for xi in x])
+        strip = 2.0 * y_wl
+        if len(x) >= 3:
+            awp = float(simpson(strip, x=x))
+            if awp > 1e-12:
+                lcf = float(simpson(strip * x, x=x)) / awp
+            else:
+                lcf = self.lpp / 2.0
+            return abs(float(simpson(strip * (x - lcf) ** 2, x=x)))
+        awp = float(np.trapz(strip, x))
+        lcf = float(np.trapz(strip * x, x)) / awp if awp > 1e-12 else self.lpp / 2.0
+        return abs(float(np.trapz(strip * (x - lcf) ** 2, x)))
+
+    def bm_transverse(self, draft: Optional[float] = None) -> float:
+        """Radio metacéntrico transversal BM_T = IT / V [m]."""
+        T = draft if draft is not None else self.draft
+        vol = self.volume_of_displacement(T)
+        return self.it_waterplane(T) / vol if vol > 1e-12 else 0.0
+
+    def bm_longitudinal(self, draft: Optional[float] = None) -> float:
+        """Radio metacéntrico longitudinal BM_L = IL / V [m]."""
+        T = draft if draft is not None else self.draft
+        vol = self.volume_of_displacement(T)
+        return self.il_waterplane(T) / vol if vol > 1e-12 else 0.0
+
+    def km_transverse(self, draft: Optional[float] = None) -> float:
+        """Altura del metacentro transversal KM_T = KB + BM_T [m].
+
+        Rawson & Tupper, "Basic Ship Theory" 5ª ed., §3.2.
+        """
+        T = draft if draft is not None else self.draft
+        return self.vcb(T) + self.bm_transverse(T)
+
+    def tpc(self, draft: Optional[float] = None, rho: float = 1025.0) -> float:
+        """Toneladas por centímetro de inmersión TPC [t/cm].
+
+        TPC = Awp · ρ / 100 000
+        Equivale a la masa añadida necesaria para aumentar el calado 1 cm.
+        """
+        T = draft if draft is not None else self.draft
+        return self.waterplane_area(T) * rho / 100_000.0
+
+    def mct1cm(
+        self,
+        draft: Optional[float] = None,
+        rho: float = 1025.0,
+        kg: Optional[float] = None,
+    ) -> float:
+        """Momento para cambiar asiento 1 cm MCT [t·m/cm].
+
+        MCT = Δ · GM_L / (100 · Lpp)
+        GM_L = KB + BM_L − KG
+
+        Si *kg* es None se usa la estimación KG ≈ depth × 0.55
+        (válida para embarcaciones con DWT vacío sin peso de carga).
+        """
+        T = draft if draft is not None else self.draft
+        if kg is None:
+            kg = self.depth * 0.55
+        gml = max(self.vcb(T) + self.bm_longitudinal(T) - kg, 0.0)
+        delta = self.displacement_tonnes(T, rho)
+        return delta * gml / (100.0 * self.lpp)
+
     # ------------------------------------------------------------------
     # Malla PyVista para visualización 3D
     # ------------------------------------------------------------------