Initial commit: Theriapolis baseline at port/godot branch point

Captures the pre-Godot-port state of the codebase. This is the rollback
anchor for the Godot port (M0 of theriapolis-rpg-implementation-plan-godot-port.md).
All Phase 0 through Phase 6.5 work is included; Phase 7 is in flight.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Theriapolis.Core/Rules/Character/HybridDetriments.cs

@@ -0,0 +1,55 @@
+namespace Theriapolis.Core.Rules.Character;
+
+/// <summary>
+/// Phase 6.5 M4 — universal Hybrid detriments, applied automatically to
+/// every <see cref="HybridState"/>-bearing character per
+/// <c>theriapolis-rpg-clades.md</c> HYBRID ORIGIN section.
+///
+/// The four detriments are *invariant rules*, not authored content —
+/// they don't vary per hybrid character — so they ship as code constants
+/// rather than a JSON content block. (Plan §3.1's "HybridDetrimentsDef
+/// loader" is documented as deviation: code constants are simpler and
+/// match the design's universality.)
+///
+/// 1. <see cref="ScentDysphoriaSaveDc"/> — WIS save DC 10 imposed on the
+///    first NPC interaction; failure → disadvantage on first CHA check.
+/// 2. <see cref="IllegibleBodyLanguagePenalty"/> — disadvantage on
+///    nonverbal CHA checks with purebred NPCs.
+/// 3. <see cref="SocialStigmaFirstCheckPenalty"/> — -2 to first CHA check
+///    with strangers in non-progressive settlements.
+/// 4. <see cref="MedicalIncompatibilityMultiplier"/> — healing from
+///    potions / Field Repair / Lay on Paws scaled by 0.75.
+/// </summary>
+public static class HybridDetriments
+{
+    /// <summary>WIS save DC for Scent Dysphoria detection check.</summary>
+    public const int ScentDysphoriaSaveDc = 10;
+
+    /// <summary>Magnitude of the Social Stigma first-CHA-check penalty (negative).</summary>
+    public const int SocialStigmaFirstCheckPenalty = -2;
+
+    /// <summary>
+    /// Multiplier applied to healing received by a hybrid character.
+    /// 0.75 = three-quarters effective per <c>clades.md</c>; round down.
+    /// </summary>
+    public const float MedicalIncompatibilityMultiplier = 0.75f;
+
+    /// <summary>True if Illegible Body Language imposes disadvantage on the given check.</summary>
+    public static bool IllegibleBodyLanguagePenalty => true;
+
+    /// <summary>
+    /// Apply the Medical Incompatibility multiplier to a heal amount when
+    /// the recipient is a hybrid PC. Round down per <c>clades.md</c>.
+    /// Non-hybrid recipients pass through unchanged.
+    /// </summary>
+    public static int ScaleHealForHybrid(Character recipient, int rawHeal)
+    {
+        if (recipient.Hybrid is null) return rawHeal;
+        if (rawHeal <= 0) return rawHeal;
+        // Round down — clades.md says "function at 75% effectiveness (round
+        // down)". (int)(0.75 * 7) = 5; (int)(0.75 * 1) = 0 → clamp to 1
+        // because "no heal" is mechanically harsher than "small heal".
+        int scaled = (int)(rawHeal * MedicalIncompatibilityMultiplier);
+        return System.Math.Max(1, scaled);
+    }
+}