Phase 3: score bar (HARE/SCOOT labels + 5 pips per side)

Draws a score bar across the top 8 rows of the multicolor bitmap at
$E000-$E13F (320 bytes), with HARE on the far left, SCOOT on the far
right, and 5 pips for each player between them.

A pip is 8x8 pixels (2 cells wide x 1 cell tall = 16 bitmap bytes):
filled = 1-pixel white border around a 6x6 black block; empty = an 8x8
white square (the border alone).  Pips are packed 2 cells each with
no gap, so adjacent pip borders merge into a 2-px white vertical
divider.

Labels use a hand-built 4x8 font (1 byte per row, top 4 bits = 4
pixels) for the 8 chars H/A/R/E/S/C/O/T (64 bytes total).  Each font
row is expanded 1bpp -> 2bpp via a 16-byte lookup table (expand4):
each '1' becomes '11' (white, from color RAM), each '0' becomes '00'
(background black, from $D021).

score_render() also rewrites the top 40 cells' attributes
(screen memory = 0, color RAM = 1) so the score bar's palette is
exactly 2 colors.  Scores are clamped to 0..5 on render to defend
against double-tap bugs in Phase 4.

src/main.c

@@ -1,11 +1,13 @@
-// main.c — Whack Hare! entry point (Phase 2: display title screen).
+// main.c — Whack Hare! entry point (Phase 3: score bar).
 //
 // Flow:
 //   1. memmap_setup()      — bank out KERNAL/BASIC/CHAR ROM.
 //   2. show_screen(TITLE)  — copy the title bitmap into $E000 and
 //                            configure the VIC for multicolor bitmap
 //                            mode.
-//   3. Loop: poll joystick port 1 for fire.  When pressed, restore
+//   3. score_init()        — zero both player scores.
+//   4. score_render()      — overlay the score bar on the top 8 rows.
+//   5. Loop: poll joystick port 1 for fire.  When pressed, restore
 //      the C64's default memory config and return from main() (which
 //      ends the program).
 //
@@ -16,13 +18,17 @@
 #include "memmap.h"
 #include "screens.h"
 #include "input.h"
+#include "score.h"
 
 int main(void)
 {
 	memmap_setup();
 	show_screen(SCREEN_TITLE);
 
-	// Phase 2: just poll for fire on port 1 (the Hare / right joystick).
+	score_init();
+	score_render();
+
+	// Phase 3: just poll for fire on port 1 (the Hare / right joystick).
 	// In Phase 4 this becomes a 50 Hz raster IRQ handler that drives the
 	// full state machine.
 	while (!input_fire(1))