docs(content): enhance linear-structures docs with detailed explanations, new problem page, updated images, and corrected array badge count

apps/docs/content/(01-linear-structures)/sliding-window/index.mdx

@@ -55,7 +55,10 @@ Without an invariant, shrinking the window becomes arbitrary. You no longer know
 The window size never changes. The main task is updating the window state efficiently when one element enters and one leaves.
 :::
 
-![Sliding Window Fixed Size](../../../public/sliding-window-fixed-size.svg)
+
+<Frame caption="Sliding Window Fixed Size" hint="">
+  <img src="../../../public/sliding-window-fixed-size.svg" alt="Sliding Window Fixed Size" />
+</Frame>
 
 ### 2. Flexible-size windows with a validity rule
 
@@ -63,8 +66,9 @@ The window size never changes. The main task is updating the window state effici
 Here the window expands until invalid, then shrinks until valid again.
 :::
 
-![Flexible-size windows](../../../public/sliding-window-flexible.svg)
-
+<Frame caption="Sliding Window Flexible" hint="">
+  <img src="../../../public/sliding-window-flexible.svg" alt="Sliding Window Flexible" />
+</Frame>
 
 ### 3. Frequency-tracking windows
 
@@ -72,7 +76,10 @@ Here the window expands until invalid, then shrinks until valid again.
 The difficulty comes from keeping the bookkeeping correct as characters enter and leave.
 :::
 
-![Frequency-tracking windows](../../../public/sliding-window-frequency.svg)
+
+<Frame caption="Frequency-tracking windows" hint="">
+  <img src="../../../public/sliding-window-frequency.svg" alt="Frequency-tracking windows" />
+</Frame>
 
 ## How Sliding Window Differs From Other Two-Pointer Families