M6.9: Cervidae + Ursidae clade rebuild

Restore the canonical clade content from theriapolis-rpg-clades.md.

Cervidae traits: Prey Sense (cannot be surprised, +WIS to initiative
twice, advantage on hidden-creature Perception), Flight Response
(reaction half-speed move on hostile-adjacent, prof-bonus uses),
Pivoting Ears (advantage hearing-Perception, cannot be flanked) —
replacing the misplaced Antlers and Fleet-Footed and the reduced
Wide Field of View. Detriments: Freeze Response (stun on first
undetected damage), Predator Aversion (CHA disadvantage near
aggressive predator clades) — replacing the misplaced clade-level
Flight Response (now correctly a trait) and Delicate Frame.

Ursidae traits: Massive Frame (size category Large outright, advantage
STR, doubled carry, Heavy weapons, one-paw -2-size grapple) —
upgrading from the reduced Powerful Build; Thick Hide (AC 12 + CON,
not the wrong 11 + DEX, dropping the un-doc'd bludgeoning resistance);
Hibernation Recovery (full hit-dice on long rest, 24-hour sleep
clears one exhaustion/disease/poison) — replacing the misplaced
Bone-Crushing Jaws (which belongs at species level on a per-bear
basis). Detriments: Ponderous (speed 25, disadvantage DEX area saves,
init -2) — restoring the speed and initiative penalties dropped by
Lumbering; Infrastructure Problem (CHA disadvantage in non-Large
spaces) — replacing the misplaced Heat Intolerance.

Migrate Delicate Frame down to Deer-Folk as Slight Frame (where the
doc puts it), since the clade-level slot is now Predator Aversion.
Heat Intolerance / Bone-Crushing Jaws drop entirely from Ursidae —
they belong on per-species records (Polar Bear's Heat Vulnerable,
Brown Bear's Devastating Swipe), which are part of audit item #5.

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

Content/Data/species.json

@@ -200,7 +200,8 @@
       { "id": "alert_eyes",            "name": "Alert Eyes",            "description": "You cannot be surprised while conscious." }
     ],
     "detriments": [
-      { "id": "skittish",              "name": "Skittish",              "description": "When taking damage from a hidden or unseen attacker, WIS save (DC 12) or use your reaction to move 10 ft. away from the attack source." }
+      { "id": "skittish",              "name": "Skittish",              "description": "When taking damage from a hidden or unseen attacker, WIS save (DC 12) or use your reaction to move 10 ft. away from the attack source." },
+      { "id": "slight_frame",          "name": "Slight Frame",          "description": "Hit point maximum reduced by 1 per level (minimum 1 HP per level). You weren't built to take hits — you were built to not be there when the hit lands." }
     ]
   },
   {