feedback5 R5: split the field-view helpers out of the render app

PIXI loading, pick records, tunables, view kind, unit info and the asset / GL
host now live in public/js/render/app/*.js. createFieldView stays in app.js,
unchanged, and every name the file used to export is re-exported. One
pixiPromise. Two source pins follow the lines that moved.

public/js/render/app/tune.js

@@ -0,0 +1,34 @@
+// public/js/render/app/tune.js — camera, drag and highlight tunables of the field view.
+
+const CAMERA_MS = 750;
+
+/** Camera pan to / from the enemy preview pen (configBlackBoard move_time 0.25). */
+export const PEN_CAMERA_MS = 250;
+
+/** Recovery of a lost 3D board context: delays of the rebuild attempts (ms) and how soon a new loss counts as failure. */
+const BOARD3D_RETRY_MS = [1200, 4000, 12000];
+
+const BOARD3D_STABLE_MS = 10000;
+
+/** Highlight groups that show a unit's range: never drawn on bench / temp pads (they are not part of any battle). */
+const RANGE_GROUPS = new Set(['facing', 'range', 'rangeStand', 'select', 'sel', 'selRange']);
+
+/**
+ * The round leader's hit tiles, lit beside an operator's range preview in the Final Assault / Hidden Core prep (see the
+ * header; community report #12 "boss受击范围可以像官方原版那样用红色"). [ASSUMED] the red and its strength: the players' request,
+ * no source shows the official colour; the range preview stays orange.
+ */
+export const LEADER_HIT_STYLE = Object.freeze({ group: 'leaderHit', color: 0xff3b30, fill: 0.3, line: 0.95 });
+
+/** atk projectile kinds whose first id is the previous bounce target (sim ai.js), not the attacker. */
+const CHAIN_KINDS = new Set(['chain', 'chainHeal']);
+
+const DROP_PENDING_MS = 1300;
+
+/**
+ * A dragged unit is held with its drawn feet this many tiles below the pointer — the pointer on its body, the model
+ * under the finger / mouse (user playtest #4 item 1: as in v2.1; mouse and touch alike). An item plate is centred on it.
+ */
+export const DRAG_HOLD_TILES = 0.45;
+
+export { CAMERA_MS, BOARD3D_RETRY_MS, BOARD3D_STABLE_MS, RANGE_GROUPS, CHAIN_KINDS, DROP_PENDING_MS };