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

TODO.md

@@ -4,6 +4,37 @@ Backlog of bugs + long-term items. Milestones live in REWORK_PLAN.md.
 
 ## Open
 
+### FEAT: critical damage button for dying/stable participants
+- Shared logic already supports `applyHpChange(..., { isCriticalHit:true })`.
+- UI only has normal Damage, which adds 1 failure at 0 HP.
+- Add button near Revive/Stabilize: **Crit Damage** / **Critical Hit**.
+- Use only for dying/stable character/NPC at 0 HP; adds 2 death-save failures.
+- Dead target remains dead; no action.
+
+### dm list - keep active particpant in view (scroll)
+
+
+#### debug feature - button to delet all campaigns - only in dev builds
+
+### bug - start/end/resume combat should not be in undo I think...
+
+### combat.js doesnt seem to actually exercise the add characters.  there are no characters in the campaign.   only in the encounter..
+
+
+## dying>stabe state - add +1hp in 1d4 hours DISPLAY (maybe show a rolled hours too) for while stable
+
+### FEAT: player display fade transitions for inactive state
+- Inactive is DM-triggered via Mark Inactive.
+- Player display should fade inactive participant out, then remove from display list.
+- Reactivating should fade participant in.
+- DM display keeps inactive participant visible.
+- Dead state does not imply inactive/disabled.
+- Dying/stable must not fade out or leave layout holes.
+- Dead can keep skull/Dead label; create some good visual cues, no removal.
+- 
+
+
+
 ### TEST GAP: current branch changes need focused coverage
 - Storage `where()` contract: firebase + server adapters should honor `[where('encounterPath','==',x), orderBy('ts','desc'), limit(n)]`.
 - Server SQL query test: `where + orderBy + limit` should return latest logs for one encounter only.
@@ -45,7 +76,12 @@ Backlog of bugs + long-term items. Milestones live in REWORK_PLAN.md.
 - Decide UX before fix.
 
 
-### death saves feature - dead PCs should not get removed from initiative! DAMMIT!
+### FEAT: generic/non-5e rules mode
+- Campaign/encounter ruleset toggle: `5e` vs `generic`.
+- Generic mode turns off death saves/state machine.
+- Generic mode allows negative HP.
+- 5e mode rejects negative damage/heal and clamps HP at 0.
+
 
 
 ### FEAT: clarify "Is NPC" in add-participant
@@ -120,12 +156,13 @@ Backlog of bugs + long-term items. Milestones live in REWORK_PLAN.md.
   case-insensitive. maxLength 40. Combat + replay tests prove arbitrary
   string ids survive round-trip.
 
-### Death saves: D&D 5e model (DONE)
-- Separate success/fail tracking. deathSave(enc, id, type, n),
-  type='success'|'fail'. Fields: deathSaves, deathFails, isStable, isDying.
-  3 success=stable, 3 fail=dead. Returns {patch, log, status, isDying}.
-  Old single-counter broken (successes missing). Old data lost (feature
-  never worked in prod). UI: green ✓ + red ✕ rows, Stabilized/Dying badges.
+### Death saves: D&D 5e status model (DONE)
+- `status` is source of truth: conscious, dying, stable, dead.
+- Characters and NPCs use death saves; monsters skip death saves and become dead/inactive at 0 HP.
+- Death-save actions: Success, Fail, Nat1, Nat20, Stabilize.
+- Revive: dead → 0 HP, stable/unconscious, active.
+- Dead characters/NPCs stay in encounter/initiative until DM removes or marks inactive.
+- Player display hides inactive participants; DM display keeps them visible.
 
 ### FEAT-3: initiative first-class entry (DONE)
 - Initiative field at add-char, add-monster, edit participant.
@@ -199,9 +236,9 @@ Backlog of bugs + long-term items. Milestones live in REWORK_PLAN.md.
 ### BUG-18: stale comments reference deleted memory adapter
 - FIXED.
 
-### FEAT-1: Dead participants stay in turn order
-- DONE --- applyHpChange no longer flips isActive on death. Dead stay in
-  rotation, nextTurn visits them, PCs get death-save turn.
+### FEAT-1: Dead characters/NPCs stay in turn order
+- DONE --- character/NPC death does not auto-remove. DM controls inactive/remove.
+- Non-NPC monsters still become inactive automatically at death.
 
 ### combat.scenario 100 rounds not turns
 - DONE --- loops by actual round-wrap count.