refactor(net): own live session composition

Extract reset, selection, entered-world, and route construction behind LiveSessionHost while preserving the sole LiveSessionController authority. Retain partial route and subscription cleanup for retry, and replace the embedded ACE-only shortcut with the exact named-retail unsigned skill formula.

Co-authored-by: Codex <codex@openai.com>

src/AcDream.App/Net/RetailSkillFormula.cs

@@ -0,0 +1,72 @@
+using DatReaderWriter.DBObjs;
+using DatReaderWriter.Types;
+
+namespace AcDream.App.Net;
+
+/// <summary>
+/// Exact unsigned formula used by retail <c>SkillFormula::Calculate @
+/// 0x00591960</c>. DAT reader fields are signed storage views, so their bits
+/// are deliberately reinterpreted as retail's unsigned W/X/Y/Z words.
+/// </summary>
+internal static class RetailSkillFormula
+{
+    public static bool TryCalculate(
+        SkillFormula formula,
+        uint attribute1,
+        uint attribute2,
+        out uint result)
+    {
+        ArgumentNullException.ThrowIfNull(formula);
+
+        uint divisor = unchecked((uint)formula.Divisor);
+        if (divisor == 0u)
+        {
+            result = 0u;
+            return false;
+        }
+
+        uint x = unchecked((uint)formula.Attribute1Multiplier);
+        uint y = unchecked((uint)formula.Attribute2Multiplier);
+        uint w = unchecked((uint)formula.AdditiveBonus);
+        uint numerator = unchecked(x * attribute1 + y * attribute2 + w);
+        result = (uint)Math.Floor((double)numerator / divisor + 0.5d);
+        return true;
+    }
+}
+
+/// <summary>
+/// Named live-session resolver for the attribute contribution to one skill.
+/// Table lookup and missing-property policy stay separate from retail math.
+/// </summary>
+internal sealed class LiveSkillCreditResolver(SkillTable? skillTable)
+{
+    public uint Resolve(
+        uint skillId,
+        IReadOnlyDictionary<uint, uint> attributeCurrents)
+    {
+        ArgumentNullException.ThrowIfNull(attributeCurrents);
+
+        if (skillTable?.Skills is null
+            || !skillTable.Skills.TryGetValue(
+                (DatReaderWriter.Enums.SkillId)skillId,
+                out var skillBase))
+        {
+            return 0u;
+        }
+
+        SkillFormula formula = skillBase.Formula;
+        attributeCurrents.TryGetValue(
+            (uint)formula.Attribute1,
+            out uint attribute1);
+        attributeCurrents.TryGetValue(
+            (uint)formula.Attribute2,
+            out uint attribute2);
+        return RetailSkillFormula.TryCalculate(
+            formula,
+            attribute1,
+            attribute2,
+            out uint result)
+            ? result
+            : 0u;
+    }
+}