Paragon: cross-class stance exclusivity + cancel, hunter ammo soft-fail, Feral Cat scaling, Pestilence DP spread

Server-side batch following v0.7.18, all gated to Paragon (or applied
server-wide where the design discussion called for it):

* Cross-class stance / form / presence / aspect exclusivity (server-wide).
  New `IsFracturedExclusiveStanceSpell()` (`Unit.cpp`/`Unit.h`) returns
  true for the union of warrior stances + druid forms (combat AND utility:
  Travel, Aquatic, Flight, Swift Flight) + Ghost Wolf + base Stealth +
  Shadowform + Metamorphosis + DK Presences + Hunter Aspects (combat AND
  utility: Cheetah, Pack). `Aura::CanStackWith` (`SpellAuras.cpp`) refuses
  to stack two spells from this set, which routes through
  `_RemoveNoStackAurasDueToAura` to drop the older aura -- the same
  mechanism Battle Elixirs / Curses use. Plugs the stock-AC gap where DK
  Presences and Hunter Aspects (regular auras, just rendered in the
  stance bar) coexisted with engine-shapeshifts.

* Stances / Presences / Aspects cancellable like Druid forms.
  `SpellInfoCorrections.cpp` now zeroes `CategoryEntry` on warrior
  stances, DK presences, and every rank of every hunter aspect (moves
  them out of SpellCategory 47 "Combat States", which gates the client's
  right-click / `/cancelaura` path), AND clears `AttributesEx6` bit
  `0x1000` on warrior stances + DK presences (a second client-UI gate
  surfaced via DBC diff -- aspects don't have it set). Mirrored client-
  side by `_patch_spell_dbc_presences_cancelable.py`. Aspects / presences
  do NOT swap action bars (those are owned by `SPELL_AURA_MOD_SHAPESHIFT`,
  not by Category / AttrEx6) -- only warrior stances and druid forms keep
  the bar swap, matching the design requirement that presences/aspects
  not change the player's action bar.

* Hunter ammo soft-fail (server-wide).
  Replaced both `SPELL_FAILED_NO_AMMO` returns in `Spell::CheckCast` with
  `break;` so ranged + thrown abilities cast through with zero ammo;
  `_ApplyAmmoBonuses` continues to gate the actual arrow/bullet DPS bonus
  on a non-empty stack, so equipping ammo still pays off. New programmatic
  `ApplySpellFix`-style block in `SpellInfoCorrections.cpp` iterates every
  Hunter-family spell whose `EquippedItemClass == ITEM_CLASS_WEAPON` and
  `EquippedItemSubClassMask` includes Bow/Gun/Crossbow and sets
  `EquippedItemClass = -1` (skipping a small DENYLIST of Quiver / Ammo
  Pouch passive haste auras + Aynasha's Bow + Legendary Bow Haste -- those
  are item-equip-driven and must keep gating on the ranged weapon being
  equipped). Server log: ">> Fractured: dropped EquippedItemClass on 196
  hunter shot abilities". Mirrored client-side by the new
  `_patch_spell_dbc_hunter_ammo.py` so the 3.3.5a client preflight stops
  blocking the cast packet with "Ammo needs to be in the paper doll ammo
  slot before it can be fired." `Spell::TakeAmmo` no longer clears
  `PLAYER_AMMO_ID` to 0 when the bag empties (defense in depth so a half-
  deployed pair degrades to soft-fail rather than hard-reject). Adds
  `#include "ItemTemplate.h"` for `ITEM_SUBCLASS_WEAPON_*`.

* Feral Cat scaling (server-wide, cat-only).
  `StatSystem.cpp` `UpdateAttackPowerAndDamage` FORM_CAT branch doubles
  the AGI coefficient (1.0 -> 2.0). `SpellAuraEffects.cpp` Master
  Shapeshifter FORM_CAT branch doubles the talent's bp before triggering
  48420 (R1: 2% -> 4% crit, R2: 4% -> 8%). FORM_BEAR / FORM_DIREBEAR /
  FORM_MOONKIN / FORM_TREE branches all left untouched so bear stays
  "already fine" per the resident Feral expert. Client tooltip drift on
  Cat Form (768) + Master Shapeshifter (48411 / 48412) + Pestilence
  (50842) handled by `_patch_spell_dbc_feral_tooltips.py`.

* Pestilence spreads / refreshes Devouring Plague for Paragon casters.
  `spell_dk.cpp` `spell_dk_pestilence::HandleScriptEffect` now also
  spreads (and Glyph-of-Disease refreshes) Priest Devouring Plague when
  `IsParagonWildcardCaller(caster)`. Uses `GetAuraOfRankedSpell(2944)` so
  the spread copy carries the caster's actual rank. Stock DKs cannot
  cast Devouring Plague at all, so this branch is a no-op for them.

* Dancing Rune Weapon: Paragon copies melee, not casts.
  `spell_dk.cpp` `spell_dk_dancing_rune_weapon::CheckProc` for Paragon
  callers requires `eventInfo.GetDamageInfo()` and
  `spellInfo->DmgClass == SPELL_DAMAGE_CLASS_MELEE`, so the ghostly
  weapon now copies cross-class melee strikes (Hamstring, Sinister Strike,
  Heart Strike, Frost Strike, ...) and auto-attacks instead of re-casting
  the DK's nukes. Stock DK gating below is untouched.

* Maelstrom Weapon: drop Arcane Blast from the allowlist.
  `SpellInfo.cpp` and `spell_shaman.cpp` allowlists now match Fireball
  and Frostbolt only -- Arcane Blast stacked with its own self-buff was
  too potent.

* `BALANCE-TODO.md` added under `contrib/fractured-dev-extras/` to
  capture the resident Feral expert's recommendation, the levers we
  considered, and the cat-only Master-Shapeshifter / AGI-doubling
  resolution we shipped, plus the next-lever knobs if field reports
  still flag cat as weak.

DBC patcher pipeline (lives outside the repo in `fractured-tooling/`)
documented run order: runes -> reagents -> stances -> presences_cancelable
-> hunter_ammo -> feral_tooltips -> _make_paragon_dbc_patch.

No SQL migrations.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/server/scripts/Spells/spell_shaman.cpp

@@ -1793,8 +1793,10 @@ class spell_sha_maelstrom_weapon : public AuraScript
     // Fractured / Paragon: spell_proc row 53817 is data-relaxed (wildcard
     // family/mask) so cross-class spells can reach this CheckProc. We
     // restore the original Shaman gating here for stock callers and add
-    // the Paragon-only Mage Fireball / Frostbolt / Arcane Blast allowlist
-    // mirroring the IsAffectedBySpellMod hook in SpellInfo.cpp.
+    // the Paragon-only Mage Fireball / Frostbolt allowlist mirroring the
+    // IsAffectedBySpellMod hook in SpellInfo.cpp. Arcane Blast was on the
+    // allowlist briefly but proved too potent stacked with its own
+    // self-buff -- removed.
     bool CheckProc(ProcEventInfo& eventInfo)
     {
         SpellInfo const* procSpell = eventInfo.GetSpellInfo();
@@ -1820,8 +1822,7 @@ class spell_sha_maelstrom_weapon : public AuraScript
             SpellInfo const* first = procSpell->GetFirstRankSpell();
             uint32 firstId = first ? first->Id : procSpell->Id;
             if (firstId == 133 /*Fireball*/
-                || firstId == 116 /*Frostbolt*/
-                || firstId == 30451 /*Arcane Blast*/)
+                || firstId == 116 /*Frostbolt*/)
                 return true;
         }