Playtest #4 fixes: tile picking, knocked-down state, element gauges, draft timer, live stats, shop items, drones, 赫默, 炎佑, UI flash

- #1 picking by the tile under the pointer (prep, battle, pen, equipment drops); the dragged model stays
  under the pointer (mouse and touch); pixel probe removed; phone ghost-click on the underframe fixed
- #2 two-tap confirm on 机变 cards (like the shop)
- #3 a 同盟 room with one human is untimed like 独立模拟 (no countdown outside battles)
- #4 strategy draft: one synced countdown, 30 s per human turn, timeout takes the highlighted band
- #5 special 维式重锤 (4) and 突变细胞 no longer sold; item card shows where they come from
- #6 operator skill-mode sounds no longer play on normal attacks (纯烬艾雅法拉 and 55 others)
- #7 detail card shows live battle stats and the prep-time battle-start stats (g.unitStats)
- #8 official element gauges on units; burst cooldown (阻回) per PRTS
- #9 knocked-down operators stay on their tile with a redeploy countdown ring
- #10 drone behaviour per PRTS (暴鸰, 先兆者 shells, 黑云, 萨科塔之眼)
- #11 赫默's drone only from her skill; placeable summons limited to talent tokens
- #12 炎佑 stays where it is with no enemies; 祛恶之焰 as a continuous channel
- #13 the occasional giant bond icon (loading texture scaled ×46) fixed
- docs (DESIGN §18), recordings, data and tests updated (2467 unit tests, all browser suites green)

test/ui/real.e2e.test.js

@@ -542,7 +542,9 @@ describe('real server + real browsers', { skip: !ENABLED && 'set SP_REAL_E2E=1 (
             const s = await c.st();
             if (s.phase === 'SP_DRAFT' && s.sp?.turn === s.me && (await c.exists('.spcard.is-pickable'))) {
               if (!seen.has(`sp-shot-${s.round}`)) { seen.add(`sp-shot-${s.round}`); await sleep(500); await c.shot(`sp-r${s.round}-${c.label}`); }
+              // two taps (user playtest #4 item 2): select, then tap the selected card again
               await c.click('.spcard.is-pickable');
+              await c.click('.spcard.is-armed');
               await c.waitFor((x) => x.sp?.turn !== x.me || x.phase !== 'SP_DRAFT', 'sp pick', 8000);
               spPicked += 1;
               c.note(`机变 picked (round ${s.round})`);