Enhance AI and simulation components with presence management and routing capabilities

- Introduced the `HSchool.Ai` project, responsible for routing, day plans, and presence management.
- Updated the `HSchool.Simulation` project to integrate with the new AI functionalities, improving decision-making and presence tracking.
- Added `travelMinutes` to room and territory definitions, ensuring accurate movement calculations within the simulation.
- Enhanced the `School` class to manage presence and implement empty-time skipping functionality.
- Updated documentation to reflect the new AI features and their impact on school simulation.
- Added tests for presence management and routing to ensure robust functionality and reliability.

src/HSchool.People/Seed.cs

@@ -4,7 +4,7 @@ namespace HSchool.People;
 /// Per-family streams derived from the school seed. Family N never consumes family N-1's rolls,
 /// so appending a thirteenth family leaves the first twelve unchanged.
 /// </summary>
-internal static class Seed
+public static class Seed
 {
     public const int ChildCountSalt = 1;
     public const int AppearanceSalt = 2;
@@ -12,6 +12,7 @@ internal static class Seed
     public const int SeatShuffleSalt = 4;
     public const int HouseholdSalt = 5;
     public const int ApplicantSalt = 6;
+    public const int CommuteSalt = 7;
 
     /// <summary>A stream that belongs to the school rather than to one family.</summary>
     public static int ForSchool(int schoolSeed, int salt) => Mix(schoolSeed, familyIndex: -1, salt);
@@ -24,6 +25,28 @@ internal static class Seed
         return (int)z;
     }
 
+    /// <summary>A stream that belongs to one person on one calendar day — commute slack, not looks.</summary>
+    public static int Mix(int schoolSeed, string personId, int dayNumber, int salt)
+    {
+        ArgumentNullException.ThrowIfNull(personId);
+        var z = Mix64((uint)schoolSeed);
+        z = Mix64(z ^ Stable(personId));
+        z = Mix64(z ^ (uint)(dayNumber + 1));
+        z = Mix64(z ^ (uint)(salt + 1));
+        return (int)z;
+    }
+
+    private static uint Stable(string value)
+    {
+        ulong z = 0;
+        foreach (var character in value)
+        {
+            z = Mix64(z ^ character);
+        }
+
+        return (uint)z;
+    }
+
     private static ulong Mix64(ulong z)
     {
         z += 0x9E3779B97F4A7C15UL;