feat(saolei): 交互玩扫雷每一步自动出 PNG

- play_saolei.tcl: k 每执行一个按键动作就存 shots/NNN_<按键>.png，并覆盖
  shots/latest.png（在 VS Code 里开着 latest.png 即可每步自动刷新）；新增 view 命令
- fb2png.py: 新增 --quiet（只写 PNG 不打印，供脚本批量截图）
- tb_saolei*.v: 仅格式调整（case 分支拆行），无语义变化
实测：k cuuuuc -> shots/001_c.png ... 006_c.png，每张 640x480 正常

pipelined-cpu/srcs/tb/tb_saolei.v

@@ -127,12 +127,16 @@ module tb_saolei;
     //   irq_rise: 该线的上升沿次数（CPU 按上升沿响应中断）
     integer ptr_ev = 0, irq_hi = 0, irq_rise = 0;
     reg     irq_prev_q;
-    initial irq_prev_q = 1'b0;
+    initial
+        irq_prev_q = 1'b0;
     always @(posedge dut.clk_cpu) begin
-        if (dut.g_btn.u_ptr.ev_valid_o) ptr_ev = ptr_ev + 1;
-        if (dut.irq_vec[0]) irq_hi = irq_hi + 1;
+        if (dut.g_btn.u_ptr.ev_valid_o)
+            ptr_ev = ptr_ev + 1;
+        if (dut.irq_vec[0])
+            irq_hi = irq_hi + 1;
         irq_prev_q <= dut.irq_vec[0];
-        if (dut.irq_vec[0] && !irq_prev_q) irq_rise = irq_rise + 1;
+        if (dut.irq_vec[0] && !irq_prev_q)
+            irq_rise = irq_rise + 1;
     end
 
     // 每毫秒打一行，观察事件链路
@@ -171,7 +175,7 @@ module tb_saolei;
                 jmp_log = jmp_log + 1;
             end
             if ((dut.u_cpu.pc_q >= 32'h0000_0194 && dut.u_cpu.pc_q < 32'h0000_0200) ||
-                (dut.u_cpu.pc_q >= 32'h0000_0218 && dut.u_cpu.pc_q < 32'h0000_0300))
+                    (dut.u_cpu.pc_q >= 32'h0000_0218 && dut.u_cpu.pc_q < 32'h0000_0300))
                 $display("[gap] %0t ns: PC 0x%03h -> 0x%03h （跳进空洞）", $time, pc_prev, dut.u_cpu.pc_q);
         end
     end
@@ -284,19 +288,29 @@ module tb_saolei;
         input integer gap_us;
         begin
             case (which)
-                0: go   = 1'b1;
-                1: btnu = 1'b1;
-                2: btnd = 1'b1;
-                3: btnl = 1'b1;
-                default: btnr = 1'b1;
+                0:
+                    go   = 1'b1;
+                1:
+                    btnu = 1'b1;
+                2:
+                    btnd = 1'b1;
+                3:
+                    btnl = 1'b1;
+                default:
+                    btnr = 1'b1;
             endcase
             #(hold_us * 1000);
             case (which)
-                0: go   = 1'b0;
-                1: btnu = 1'b0;
-                2: btnd = 1'b0;
-                3: btnl = 1'b0;
-                default: btnr = 1'b0;
+                0:
+                    go   = 1'b0;
+                1:
+                    btnu = 1'b0;
+                2:
+                    btnd = 1'b0;
+                3:
+                    btnl = 1'b0;
+                default:
+                    btnr = 1'b0;
             endcase
             #(gap_us * 1000);
         end