Add AC field (character, monster/npc, participant edit); layout polish

AC (Armor Class) optional field across all participant entry points:
- shared: ac field on makeParticipant + buildMonsterParticipant +
  buildCharacterParticipant, defaults null
- CharacterManager: defaultAc state + add form field + inline edit field +
  display in character list
- Monster add form: AC field
- EditParticipantModal: AC field next to Initiative
- ParticipantManager (DM list): AC badge on name row (sky-blue, stylized,
  large value, small label) for at-a-glance reading
- Player display: no AC (DM only)

Layout polish:
- Add participants form: 12-col grid, 5 fields single row (Init Mod, Initiative,
  AC, Max HP, HP Formula), shrunk from oversized fields
- Character add form: 12-col grid, name grows (col-span-6), Init Mod/AC/HP
  small right-aligned, order matches add participants
- Character inline edit: labels added (Name/HP/Init Mod/AC), name flex-grows
- HP Formula: label trimmed (example moved to placeholder 'e.g. 2d6+9'),
  Reroll button in edit modal
- ParticipantManager init input shrunk (w-8, centered)

Tests: 6 new AC builder tests (turn.ac.test.js). Existing test labels updated
for renamed fields.

TODO.md

@@ -9,12 +9,13 @@ fullscreen and dont lock on main app dm view and the no-game-player view
 
 also better vert tab layout - labelt friendly
 
-needs AC for players dude
+x needs AC for players dude
 
 and quick entry hp
 
 hp do not carry from encounter to ecnounter!!!
-
+^feature to add back to campaign character after encounter?
+maybe campaign toggle in charc section (choosing each end is DM overload will be missed forgotten done wront)
 
 hp wont go over max and no temp hp support