feat: Refactor Poison system, implement Darkglow & Parasitic effects (#2385)

## Summary

- Refactors the poison system to separate `Index` (globally unique ID) from `Level` (tier within a family), enabling multiple poison families (Standard, Darkglow, Parasitic) to coexist without collisions
- Implements Darkglow and Parasitic poison special effects from Mondain's Legacy: Darkglow boosts damage by 10% when attacker is ranged, Parasitic heals the attacker for damage dealt in melee range
- Fixes several bugs: `Register()` crashing on duplicate `Level` values across families, `IncreaseLevel()` crossing family boundaries, `InfectiousStrike` and `NinjaWeapons` stripping poison family via level-based lookups, and `ArchCure`/`CleansingWinds` using raw `Level + 1` instead of `IncreaseLevel()`

## Changes

**`Projects/Server/Poison.cs`** — Adds `PoisonFamily` enum and abstract `Family` property. Adds `Index` as unique identifier. Fixes `Register()` to check `Index` uniqueness (not `Level`) and validate the new poison's name (not the existing one's). Fixes `IncreaseLevel()` to use `Index + 1`, naturally respecting family boundaries via Index gaps. Replaces linear name lookup with `Dictionary`-based `PoisonsByName`.

**`Projects/UOContent/Misc/Poison.cs`** — Adds `family` parameter to `PoisonImpl`. Implements Darkglow effect (10% damage boost when `From` >1 tile, cliloc 1072850) and Parasitic effect (heals `From` for damage dealt within 1 tile, cliloc 1060203) in `PoisonTimer.OnTick()`. Renames `m_` fields to `_` convention.

**`Projects/UOContent/Misc/PoisonKinds.cs`** — New file. Moves poison registration out of `PoisonImpl` into `PoisonKinds.Configure()`. Adds `PoisonFamily` to Darkglow/Parasitic registrations. Provides extension properties (`Lesser`, `Deadly`, `LesserDarkglow`, etc.), `GetPoison(int level)` (standard-only), `GetPoisonByFamilyAndLevel()`, and `IsDarkglow`/`IsParasitic` instance helpers.

**`Projects/UOContent/Items/Weapons/Abilities/InfectiousStrike.cs`** — Family-aware poison scaling: Darkglow caps at Deadly (Poisoning/33.3), Parasitic caps at Lethal (Poisoning/25), Standard unchanged. Level bump uses `IncreaseLevel()` with family boundary check.

**`Projects/UOContent/Items/Skill Items/Ninjitsu/NinjaWeapons.cs`** — EvilOmen level bump uses `Poison.IncreaseLevel()` instead of `Poison.GetPoison(Level + 1)`.

**`Projects/UOContent/Spells/Fourth/ArchCure.cs`** and **`CleansingWindsSpell.cs`** — Replace `poison.Level + 1` with `Poison.IncreaseLevel(poison).Level` for family-safe cure chance calculation.

**`Projects/Server/Serialization/SerializationExtensions.cs`** — Serializes/deserializes `Index` instead of `Level`.

**`DarkglowPotion.cs`** / **`ParasiticPotion.cs`** — Point to actual Darkglow/Parasitic poisons instead of placeholder `Greater`.

**`PotionKeg.cs`** / **`BasePotion.cs`** — Adds Darkglow, Parasitic, Invisibility, and FlintsPungentBrew to `PotionEffect` enum and keg label support.

## Test plan

- [ ] `dotnet build` compiles cleanly (verified, 0 warnings 0 errors)
- [ ] Verify `PoisonKinds.Configure()` registers all poisons without throwing (Register bug fix)
- [ ] Standard poison behavior unchanged — PoisonField, PoisonSpell, SerpentArrow, SavageShaman, TrappableContainer all use `GetPoison(int level)` which now correctly filters to Standard family
- [ ] Darkglow: poison tick deals +10% damage when attacker is >1 tile away, sends "Darkglow poison increases your damage!" message
- [ ] Parasitic: poison tick heals attacker for damage dealt when within 1 tile, sends heal message
- [ ] InfectiousStrike preserves poison family and respects family-specific skill scaling
- [ ] EvilOmen + NinjaWeapons level bump stays within poison family
- [ ] ArchCure/CleansingWinds cure chance calculations work correctly across all poison families
- [ ] Serialization round-trips correctly using Index

Projects/UOContent/Items/Weapons/Abilities/InfectiousStrike.cs

@@ -46,25 +46,30 @@ namespace Server.Items
 
             --weapon.PoisonCharges;
 
+            var poisoningSkill = attacker.Skills.Poisoning.Value;
+
             // Infectious strike special move now uses poisoning skill to help determine potency
-            var maxLevel = Math.Max((int)(attacker.Skills.Poisoning.Value / 20), 0);
+            var family = p.Family;
+
+            int maxLevel = family switch
+            {
+                PoisonFamily.Darkglow  => Math.Min((int)(poisoningSkill / 33.3), 3),
+                PoisonFamily.Parasitic => Math.Min((int)(poisoningSkill / 25), 4),
+                _                      => Math.Max((int)(poisoningSkill / 20), 0)
+            };
+
             if (p.Level > maxLevel)
             {
-                p = Poison.GetPoison(maxLevel);
+                p = Poison.GetPoisonByFamilyAndLevel(family, maxLevel);
             }
 
-            if (attacker.Skills.Poisoning.Value / 100.0 > Utility.RandomDouble())
+            // Check if the poison can be increased.
+            var newPoison = Poison.IncreaseLevel(p);
+            if (newPoison != p && poisoningSkill / 100.0 > Utility.RandomDouble())
             {
-                var level = p.Level + 1;
-                var newPoison = Poison.GetPoison(level);
-
-                if (newPoison != null)
-                {
-                    p = newPoison;
-
-                    attacker.SendLocalizedMessage(1060080); // Your precise strike has increased the level of the poison by 1
-                    defender.SendLocalizedMessage(1060081); // The poison seems extra effective!
-                }
+                p = newPoison;
+                attacker.SendLocalizedMessage(1060080); // Your precise strike has increased the level of the poison by 1
+                defender.SendLocalizedMessage(1060081); // The poison seems extra effective!
             }
 
             defender.PlaySound(0xDD);