games: revert to 60 fps, slower Snake base speed

Switched both games back to 60 fps (FRAME_MS = 16 ms) for smoother rendering
and reduced Snake base speed from 150 to 90 px/sec (~60 ms -> ~100 ms per
step at cell=9) so the snake is controllable and doesn't feel too fast.
Progressive difficulty (+1 px/sec per 5 food) and turn queue are unchanged.

src/games/snake.cpp

@@ -107,8 +107,8 @@ static int tqn = 0;                // number of queued turns
 static int foodx, foody;
 static int score = 0;
 static int best = 0;
-static int speed = 90;             // ms per step (derived from pps below)
-static int pps = 150;              // base speed px/sec; +1 px/sec per 5 food eaten
+static int speed = 100;            // ms per step (derived from pps below)
+static int pps = 90;               // base speed px/sec; +1 px/sec per 5 food eaten
 static unsigned long nextTick = 0;
 static bool running = true;
 static unsigned long now_ms() {
@@ -166,7 +166,7 @@ static void reset_game() {
   dirx = 1; diry = 0;
   tqn = 0;
   score = 0;
-  pps = 150;
+  pps = 90;
   update_speed();
   place_food();
   state = PLAYING;
@@ -224,7 +224,7 @@ static void step() {
     score += 10;
     if (score > best) best = score;
     int food = score / 10;        // food items eaten so far
-    pps = 150 + food / 5;          // +1 px/sec per 5 food eaten (progressive difficulty)
+    pps = 90 + food / 5;          // +1 px/sec per 5 food eaten (progressive difficulty)
     update_speed();
     place_food();
   }
@@ -407,7 +407,7 @@ int main() {
   render();
 
   int xfd = ConnectionNumber(dpy);
-  const unsigned long FRAME_MS = 1000 / 30;  // 30 fps rendering
+  const unsigned long FRAME_MS = 1000 / 60;  // 60 fps rendering
   unsigned long frameStart = now_ms();
 
   while (running) {

src/games/tetris.cpp

@@ -520,7 +520,7 @@ int main() {
   render();
 
   int xfd = ConnectionNumber(dpy);
-  const unsigned long FRAME_MS = 1000 / 30;  // 30 fps rendering
+  const unsigned long FRAME_MS = 1000 / 60;  // 60 fps rendering
   unsigned long frameStart = now_ms();
 
   while (running) {