Implement D&D 5e death-save state machine and cleanup combat ordering

- Add status-driven death-save model:
  - status: conscious | dying | stable | dead
  - deathSaveSuccesses/deathSaveFailures as display counters
  - remove old death-save fields as source of truth
- Add death-save actions:
  - success, fail, nat1, nat20
  - stabilize participant
  - revive dead participant to 0 HP, stable, unconscious
- Apply 5e HP transition rules:
  - characters and NPCs at 0 HP become dying
  - stable/dying participants gain unconscious condition
  - healing clears death saves and returns conscious
  - massive damage kills
  - non-NPC monsters at 0 HP become dead and inactive
- Split NPCs from monsters with type="npc":
  - NPCs use death saves like characters
  - NPCs remain DM-controlled/monster-colored in UI
  - new NPCs no longer persist isNpc flag
- Keep dead PCs/NPCs in encounter and initiative until DM removes or deactivates
- Allow DM active/inactive toggle for dead participants
- Hide inactive participants from player display
- Improve DM and player death-state UI:
  - show Dying/Dead/Unconscious states consistently
  - add revive button for dead participants
  - distinguish dead visual from inactive visual in DM view
- Fix initiative drag/reorder behavior:
  - downward drag now changes order instead of no-op
  - paused combat can reorder across current turn pointer
  - turnOrderIds stay synced to participants order
- Persist campaign collapse state in localStorage
- Update death-save docs and encounter builder docs
- Add/expand tests for:
  - death saves and HP transitions
  - dead/active/inactive behavior
  - NPC death-save behavior
  - player display visibility
  - drag reorder semantics
  - logging expectations

Tests:
- npm run test:all
- app: 94 passed
- shared: 158 passed, 5 skipped
- server: 32 passed

docs/ENCOUNTER_BUILDER.md

@@ -53,16 +53,16 @@ Object in `encounter.participants[]`:
 |---|---|---|
 | `id` | string | `generateId()` |
 | `name` | string | |
-| `type` | `'character'` \| `'monster'` | character = PC (death saves), monster = hostile/NPC |
+| `type` | `'character'` \| `'npc'` \| `'monster'` | character/NPC = death saves, monster = dead at 0 HP |
 | `originalCharacterId` | string\|null | links back to campaign character if type=character |
 | `initiative` | int | rolled once at add (`rollD20() + mod`). Stored value, not re-derived. |
 | `maxHp` | int | |
-| `currentHp` | int | 0 = dead/dying |
-| `isNpc` | bool | monster flagged NPC (display color, no death saves) |
+| `currentHp` | int | 0 = dead/dying/stable by `status` |
 | `conditions` | array | condition ids from `CONDITIONS` list |
 | `isActive` | bool | in turn rotation? false = skipped by nextTurn |
-| `deathSaves` | int | PC only, 0-3 fails |
-| `isDying` | bool | death animation flag (player display) |
+| `status` | `'conscious'` \| `'dying'` \| `'stable'` \| `'dead'` | death-save source of truth |
+| `deathSaveSuccesses` | int | character/NPC only, 0-3 successes |
+| `deathSaveFailures` | int | character/NPC only, 0-3 failures |
 
 ## Build flow (UI)
 
@@ -99,7 +99,7 @@ ParticipantManager section. Two paths:
 - **Monster Name** (`placeholder: "e.g., Dire Wolf"`)
 - **Init Mod** (`MONSTER_DEFAULT_INIT_MOD` = 2)
 - **Max HP** (`DEFAULT_MAX_HP` = 10)
-- **Is NPC?** checkbox (flag, changes display color)
+- **Is NPC?** checkbox (sets `type: 'npc'`, keeps monster/DM-control color, enables death saves)
 - Click **Add to Encounter**
 - Initiative auto-rolled: `rollD20() + mod`
 
@@ -113,13 +113,13 @@ ParticipantManager section. Two paths:
 Participant object added:
 ```js
 { id, name, type, originalCharacterId, initiative, maxHp, currentHp:maxHp,
-  isNpc, conditions:[], isActive:true, deathSaves:0, isDying:false }
+  conditions:[], isActive:true, status:'conscious', deathSaveSuccesses:0, deathSaveFailures:0 }
 ```
 
 ### 6. Reorder before start (tie-break)
 Pre-combat only (`!isStarted || isPaused`). Drag handles shown for **tied initiative** values only. Drop reorders `participants[]` + `turnOrderIds`.
 
-Post-start drag: see BUG-13/14 in `TODO.md` (cross-init + pointer semantics untested).
+During active combat, cross-current-pointer drag is blocked to avoid skip/double-act ambiguity. Paused combat can reorder same-initiative ties freely.
 
 ## Combat flow (UI)
 
@@ -135,8 +135,9 @@ InitiativeControls panel (sticky, right side).
 ### Next Turn
 - **Next Turn** button (disabled if paused)
 - Advances to next active participant in `turnOrderIds`
-- Wraps at end → `round += 1`, re-sorts active by initiative at round start
-- Dead (`isActive:false`) skipped, stay in rotation
+- Wraps at end → `round += 1`
+- No re-sort after start; 1-list order remains source of truth
+- Inactive (`isActive:false`) participants are skipped, but stay in slot
 
 ### Pause / Resume
 - **Pause Combat** → `isPaused=true`, Next Turn disabled
@@ -147,11 +148,19 @@ InitiativeControls panel (sticky, right side).
 Per-participant input + buttons:
 - Number input
 - **Damage** (HeartCrack icon) — `currentHp = max(0, hp - amt)`
-- **Heal** (Heart icon) — `currentHp = min(maxHp, hp + amt)`
-- Death: hp→0 sets `isActive:false`, PC gets `deathSaves` tracking
+- **Heal** (Heart icon) — `currentHp = min(maxHp, hp + amt)` for living/dying/stable participants; normal heal does not affect dead participants
+- Character/NPC at 0 HP → `status:'dying'`, death-save controls, unconscious condition
+- Monster at 0 HP → `status:'dead'`, `isActive:false`
+- Massive damage (`damage >= currentHp + maxHp`) → dead
 
-### Death saves (PC only, at 0 HP)
-3 buttons. Click marks fail. 3 fails = dead. Reset on revive/heal.
+### Death saves (character/NPC only, at 0 HP)
+Action buttons: Success, Fail, Nat1, Nat20, Stabilize.
+- Success: +1 success; 3 successes → stable/unconscious at 0 HP
+- Fail: +1 failure; 3 failures → dead
+- Nat1: +2 failures
+- Nat20: 1 HP, conscious, counters reset
+- Stabilize: stable/unconscious at 0 HP, counters reset
+- Revive: dead → 0 HP, stable/unconscious, active
 
 ### Conditions
 - Click participant → expand conditions picker (all 22 from `CONDITIONS`)
@@ -170,7 +179,7 @@ What it shows:
 - Round + current turn participant
 - All participants in `participants[]` order (drag order, NOT init-sorted — BUG-15 fix)
 - HP bars, conditions, death saves
-- Inactive monsters hidden (pre-staged reserves)
+- Inactive participants hidden (including auto-inactive dead monsters and DM-hidden reserves)
 
 Driven by `activeDisplay/status` doc. Controlled by **Open Player Window** button (sets active campaign+encounter) or Start Combat (auto-sets).
 
@@ -181,11 +190,11 @@ Key architecture. `turnOrderIds === participants.map(p => p.id)` always. Single
 - **Display** = `participants[]` order (AdminView + DisplayView, no re-sort)
 - **Turn rotation** = `turnOrderIds` (mirrors participants[])
 - **Drag** = source of truth, overrides initiative
-- **Add mid-combat** = append to participants[] + sync (BUG-14: init-insert broken post-drag)
+- **Add mid-combat** = slot by initiative into participants[] + sync
 - **Toggle active** = flip `isActive` only, stay in slot
 - **Remove** = drop from participants[] + sync, advance current if needed
 
-No re-sort after `startEncounter` except round-wrap (re-sorts active by init at top of round).
+No re-sort after `startEncounter`.
 
 ## Storage paths quick reference
 
@@ -202,7 +211,8 @@ logs/{logId}                                 action log entry
 - Initiative rolled ONCE at add time. Stored. Edit via EditParticipantModal to override.
 - Pause before big roster changes (adds/removes). Resume re-syncs cleanly.
 - Campaign chars = templates. Edit campaign char doesn't touch encounter participants (already added).
-- Dead monsters stay in rotation, skipped. Remove via trash icon to clean list.
+- Dead monsters become inactive automatically and are skipped. Remove via trash icon to clean list.
+- Dead characters/NPCs stay active until DM marks inactive, removes, or revives them.
 - Player display auto-follows Start Combat. Manual control via Open Player Window.
 
 See `docs/GLOSSARY.md` for domain terms, `TODO.md` for known bugs.