Add sliding-window module: 12 sliding window and two-pointer interview problems, brute-force cross-checks, dry-run traces, operation counts, pitfalls (11 tests)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b6EqSkUWKNBc8i3Q3U

sliding-window/output/02-longest-unique-trace.txt

@@ -0,0 +1,21 @@
+Longest substring without repeating characters
+==============================================
+
+input "abcabcbb"
+  right=0 'a'  left=0  window="a"  best=1
+  right=1 'b'  left=0  window="ab"  best=2
+  right=2 'c'  left=0  window="abc"  best=3
+  right=3 'a'  left=1  window="bca"  best=3  seen at 0 inside the window, left 0 -> 1
+  right=4 'b'  left=2  window="cab"  best=3  seen at 1 inside the window, left 1 -> 2
+  right=5 'c'  left=3  window="abc"  best=3  seen at 2 inside the window, left 2 -> 3
+  right=6 'b'  left=5  window="cb"  best=3  seen at 4 inside the window, left 3 -> 5
+  right=7 'b'  left=7  window="b"  best=3  seen at 6 inside the window, left 5 -> 7
+  answer = 3
+
+input "abba"
+  right=0 'a'  left=0  window="a"  best=1
+  right=1 'b'  left=0  window="ab"  best=2
+  right=2 'b'  left=2  window="b"  best=2  seen at 1 inside the window, left 0 -> 2
+  right=3 'a'  left=2  window="ba"  best=2  seen at 0 but that is left of the window, left stays 2
+  answer = 2
+