refactor starcontrol weapons and improve road visibility

- Rewrite Kohr-Ah guidedBlades: one-shot-per-press with blades that fly
  straight while held, then slow and become homing mines near enemies;
  blades persist indefinitely and cap at 8 live (oldest recycled)
- Add bladeFireHeld tracking and canFire/tick hooks for blade cooldown
- Update AI to tap fire for Kohr-Ah blades instead of holding
- Reduce PLANET_GRAVITY from 1.6e6 to 1.1e6 for better slingshot physics
- Add dark outline pass under road/rail lines in Civilization map for
  better visibility against light terrain

src/games/civilization/CivilizationMapView.js

@@ -344,7 +344,7 @@ export class CivilizationMapView {
     if (bits & (IMP.ROAD | IMP.RAILROAD)) {
       g.clear();
       const rail = !!(bits & IMP.RAILROAD);
-      let drewAny = false;
+      const segments = [];
       for (let dy = -1; dy <= 1; dy += 1) {
         for (let dx = -1; dx <= 1; dx += 1) {
           if (dx === 0 && dy === 0) continue;
@@ -355,21 +355,24 @@ export class CivilizationMapView {
           if (!(nBits & (IMP.ROAD | IMP.RAILROAD))) continue;
           const ex = (this.isoX(nc, nr) - this.isoX(c, r)) / 2;
           const ey = (this.isoY(nc, nr) - this.isoY(c, r)) / 2;
-          g.lineStyle(rail ? 4 : 3, rail ? 0x4a4038 : 0x8a6f4d, 0.9);
-          g.beginPath();
-          g.moveTo(0, cy);
-          g.lineTo(ex, cy + ey);
-          g.strokePath();
-          drewAny = true;
+          segments.push([ex, cy + ey]);
         }
       }
-      if (!drewAny && !hasCity) {
-        g.lineStyle(3, 0x8a6f4d, 0.9);
-        g.beginPath();
-        g.moveTo(-14, cy);
-        g.lineTo(14, cy);
-        g.strokePath();
-      }
+      if (!segments.length && !hasCity) segments.push([-14, cy], [14, cy]);
+      // A dark outline pass under the road/rail colour itself makes the line
+      // read clearly against any terrain, instead of blending in on lighter
+      // ground like desert/plains.
+      const strokeAll = (width, color, alpha) => {
+        g.lineStyle(width, color, alpha);
+        for (const [ex, ey] of segments) {
+          g.beginPath();
+          g.moveTo(0, cy);
+          g.lineTo(ex, ey);
+          g.strokePath();
+        }
+      };
+      strokeAll(rail ? 7 : 6, 0x000000, 0.4);
+      strokeAll(rail ? 4 : 3, rail ? 0x4a4038 : 0x8a6f4d, 1);
       this.drawStampAt(g, x, y);
     }
 

src/games/starcontrol/StarControlAI.js

@@ -340,6 +340,11 @@ export function updateAI(ai, state, dtMs) {
       && !(enemy.fx.cloaked && dist > 900)) {
     input.fire = true;
   }
+  // Kohr-Ah blades are one-shot-per-press: the ship must let go of the
+  // button before it can launch another, so tap it instead of holding it.
+  if (ship.def.primary.type === 'guidedBlades' && ship.fx.bladeFireHeld) {
+    input.fire = false;
+  }
   // Charge weapons (Melnorme pump-up): keep pumping while far or unaimed,
   // release once the shot is charged and the nose is on target.
   if (ship.fx.pump) {

src/games/starcontrol/StarControlLogic.js

@@ -22,7 +22,7 @@ export const FACING_STEP = (Math.PI * 2) / FACINGS;
 export const TUNE = {
   MAX_FRAMES_PER_STEP: 6,        // spiral-of-death cap after tab suspend
   PLANET_RADIUS: 220,            // world units (UQM planet ~29 display px)
-  PLANET_GRAVITY: 1.6e6,         // accel = G / r^2 (world units / frame^2)
+  PLANET_GRAVITY: 1.1e6,         // accel = G / r^2 (world units / frame^2)
   PLANET_GRAVITY_MIN_R: 420,     // clamp radius so slingshots stay sane
   PLANET_CREW_DAMAGE: 3,         // crew lost on planet impact
   PLANET_DAMAGE_COOLDOWN: 24,    // frames between crew-damaging planet hits

src/games/starcontrol/StarControlShips.js

@@ -318,23 +318,56 @@ export const PRIMARIES = {
     },
   },
 
-  // Kohr-Ah spinning blades: launched forward, then steered toward wherever
-  // the Marauder points while the button is held.
+  // Kohr-Ah spinning blades: one shot per button press (the button must be
+  // released before another blade can launch), launched dead ahead and left
+  // flying straight while the button stays held. Releasing lets a blade
+  // coast to a stop and then drift as a slow homing mine toward any enemy
+  // that strays close, otherwise it just sits there as a trap. Blades never
+  // expire on their own — only dying to a ship, asteroid, planet or another
+  // blade — but only maxCount (default 8) may be live at once; launching
+  // past that cap pops the oldest.
   guidedBlades: {
     fire(state, ship, def) {
+      ship.fx.bladeFireHeld = true;
       const m = muzzle(ship, (def.muzzleDist ?? 9) * 4, 0);
-      spawnProjectile(state, ship, {
+      const blade = spawnProjectile(state, ship, {
         type: 'blade',
         x: m.x, y: m.y, angle: m.angle,
         speed: def.speed,
-        damage: def.damage, hp: def.hp ?? 10, life: def.lifeFrames,
+        damage: def.damage, hp: def.hp ?? 10, life: Infinity,
         radius: def.radius ?? 30,
+        data: { trackRange: (def.trackRange ?? 224) * 4, wait: 0 },
         behavior(st, p) {
           const owner = st.ships[p.owner];
-          if (!owner.alive || !owner.input.fire) return;
-          steerProjectile(p, facingToRad(quantizeFacing(owner.facing)), FACING_STEP / 2, def.speed);
+          if (owner.alive && owner.input.fire) return;
+          if (Math.abs(p.vx) > 1 || Math.abs(p.vy) > 1) {
+            p.vx *= 0.5; p.vy *= 0.5;
+            return;
+          }
+          p.vx = 0; p.vy = 0;
+          if (p.data.wait > 0) { p.data.wait -= 1; return; }
+          p.data.wait = 4;
+          const enemy = enemyOf(st, owner);
+          if (!enemy.alive || tdist(p.x, p.y, enemy.x, enemy.y) > p.data.trackRange) return;
+          const a = bearingTo(p, enemy);
+          p.vx = Math.cos(a) * 8; p.vy = Math.sin(a) * 8;
         },
       });
+      const blades = (ship.fx.blades ?? []).filter((b) => b.alive);
+      blades.push(blade);
+      const max = def.maxCount ?? 8;
+      while (blades.length > max) {
+        const oldest = blades.shift();
+        oldest.alive = false;
+        emit(state, { t: 'shotHit', x: oldest.x, y: oldest.y, kind: 'blade' });
+      }
+      ship.fx.blades = blades;
+    },
+    canFire(state, ship) {
+      return !ship.fx.bladeFireHeld;
+    },
+    tick(state, ship) {
+      if (!ship.input.fire) ship.fx.bladeFireHeld = false;
     },
   },