feat: add dynamic ship tracking for sentences mode

- Ship now moves to center of each character as you type
- Calculate and store X position of current character during rendering
- Ship smoothly tracks typing progress across both lines
- Handles line transitions seamlessly
- Creates engaging targeting effect as ship 'shoots' each letter

src/types.ts

@@ -37,6 +37,8 @@ export type FallingLetter = {
   // For line transitions in sentences/paragraphs
   lineTransition?: boolean;
   lineTransitionTime?: number;
+  // For ship tracking in sentences
+  currentCharX?: number; // X position of current character to type
 };
 
 // ============================================================================

src/useBoard/useBoard.ts

@@ -359,6 +359,8 @@ export function useBoard() {
                 ctx.fillStyle = `rgba(0, 255, 0, ${topOpacity})`; // Green - completed
               } else if (charIdx === charIndex) {
                 ctx.fillStyle = `rgba(255, 255, 0, ${topOpacity})`; // Yellow - current
+                // Store position of current character for ship tracking
+                letter.currentCharX = line2X + ctx.measureText(char).width / 2;
               } else {
                 ctx.fillStyle = `rgba(255, 255, 255, ${topOpacity})`; // White - remaining
               }
@@ -380,6 +382,8 @@ export function useBoard() {
                     ctx.fillStyle = "#00ff00"; // Green - completed
                   } else if (i === charIndex) {
                     ctx.fillStyle = "#ffff00"; // Yellow - current
+                    // Store position of current character for ship tracking
+                    letter.currentCharX = line1X + ctx.measureText(char).width / 2;
                   } else {
                     ctx.fillStyle = "#ffffff"; // White - remaining
                   }

src/useGame/useGame.ts

@@ -28,7 +28,7 @@ export function useGame(
     gameStatusManager.updatePlayerX(playerPos.x);
 
     // For words/letters, auto-track to falling letters
-    // For sentences/paragraphs, keep ship centered
+    // For sentences/paragraphs, track to current character position
     if (gameModeRef.current !== 'sentences' && gameModeRef.current !== 'paragraphs') {
       if (letters.length > 0) {
         const letter = letters[0];
@@ -37,9 +37,16 @@ export function useGame(
       
       cursorManager.moveTowardTarget(deltaTime);
     } else {
-      // Keep ship centered for sentence/paragraph mode
-      cursorManager.setTargetX(400); // Canvas center
-      cursorManager.moveTowardTarget(deltaTime); // Move to center but don't track letters
+      // For sentences: track to current character position
+      if (letters.length > 0) {
+        const letter = letters[0];
+        // Use the stored character position or default to center
+        const targetX = letter.currentCharX || 400;
+        cursorManager.setTargetX(targetX);
+      } else {
+        cursorManager.setTargetX(400); // Default to center when no letters
+      }
+      cursorManager.moveTowardTarget(deltaTime);
     }
     
     renderBoardWrapped(letters);