feedback1 WD: forms reach late views, stable enemy shapes, review fixes

- Every form change goes through content setForm(): the unit keeps it (e.form)
  and UnitInfo publishes it, so a view built mid-battle from fieldMeta (a
  watched teammate's field, 联防 observers, a reconnect) starts in the
  current form instead of the first-form model.
- Enemy profile (dmgType) and Unit moving / form are initialised at spawn:
  one object shape for the sim's hot loop (the boss-field bench is back at
  the base speed).
- 转译基底·α: an HP loss cannot knock out its original form (no death clip).
- 假想敌：再生: 1 s 重生 and walking 傀儡 cited from PRTS; shields within 1.8
  as the 再生状态 begins.
- Renderer: a 重生's closing clip (and the ember's stand-up clip) is timed
  from the fx dur to end with it, so the next form attacks on its own clips.
- Docs: ASSETS FORMS list, SIM form fx, PLAYING 隐匿 wording.

server/sim/units.js

@@ -81,6 +81,8 @@ export class Unit {
     this.trait = {};            // profession runtime state
     this.stats = { dmg: 0, kills: 0, heal: 0, taken: 0, attacks: 0 };
     this.hidden = false;        // enemies inside a DISAPPEAR segment
+    this.moving = false;        // enemies: walked this tick (drawn on the move clip; ai.js updateEnemy)
+    this.form = null;           // enemies: the model's current form (content/enemies.js setForm → snapshot.js unitInfo)
     this.anim = 0;
     this.persist = { redeployMul: 1, freeRedeploys: 0 };
     this.isBoss = false;