Normalize ammo economy: per-weapon refill, stream drain, behavior fixes

- Every special weapon gets an explicit 'refill' (units per ammo pickup,
  tuned so one pickup funds ~10 kills) replacing the ammoRefillFraction
  log2 heuristic and ammoWeight overrides
- Bile Blunderbuss + The Cauterizer join Red Right Hand as time-denominated
  stream weapons ('drain' per second) instead of per-shot cost
- Sawblades ricochet through enemies (bounce fix), traps catch 3 victims,
  lobbed projectiles arc overhead and always trigger at the target point
  (Flesh Masher / Trap Queen / Swarm Jar payloads now actually deploy)
- Boss rooms stock one ammo on entry and drop one guaranteed on death
- Cauterizer burn trimmed (2.2s x2 -> 1.5s x0.8), bile acid pools trimmed
  (3.5s x1.5 -> 2.5s x0.8), Marrow Draught now covers stream drain
- New tools/ammo_sim.js calibrates every weapon into the 8-13 kills/refill
  band (all 15 pass); smoke test guards the ammo structure
- v0.3.0, cache bump v=44

js/help.js

@@ -151,7 +151,9 @@ function drawHelpArsenal(ctx, px, py) {
     if (row % 2 === 0) { ctx.fillStyle = 'rgba(255,220,200,0.03)'; ctx.fillRect(x - 4, ty - 11, HELP_PANEL.w - 72, 15); }
     const dps = Math.round(w.dmg / Math.max(0.01, w.interval) * (w.pellets || 1));
     const vals = [w.name.toUpperCase(), w.tier < 0 ? 'SIDE' : 'T' + w.tier, String(w.dmg),
-      w.interval.toFixed(2) + 's', w.ammo === Infinity ? '∞' : String(w.ammo), String(dps), w.behavior.toUpperCase()];
+      w.interval.toFixed(2) + 's',
+      w.ammo === Infinity ? '∞' : (w.drain ? w.ammo + '·' + w.drain + '/s' : String(w.ammo)),
+      String(dps), w.behavior.toUpperCase()];
     ctx.fillStyle = '#c9b8ae';
     for (let c = 0; c < cols.length; c++) ctx.fillText(vals[c], x + cols[c], ty);
     ty += 15;