feat(others): add sliding window maximum with edge-case handling

[hemanth2k6]

Description

Added the "Sliding Window Maximum" algorithm to the others/ directory. The solution uses a monotonic deque approach to optimize lookup efficiency down to linear time.

Type of Change

• New algorithm implementation
• Defensive edge-case handling additions

Complexity

• Time Complexity: $\mathcal{O}(N)$ where $N$ is the total number of elements.
• Space Complexity: $\mathcal{O}(K)$ where $K$ is the window size.

Validation & Testing Done

• Added robust assertions inside the execution block (static void test()).
• Validated defensive guard clauses against:
  1. Completely empty vectors (nums = {})
  2. Sub-zero or zero window sizes (k <= 0)
  3. Window configurations scaling larger than the array size (k > nums.size())
• Registered the target inside others/CMakeLists.txt to guarantee clean automated compilation builds.

Closes #4092