docs(help): add descriptions, comparisons, and use-cases for heaps, shell sort, and queues

[vedant-kawale-27]

PR Description:

Overview

This PR completes the help documentation for several modules by adding missing descriptions, theoretical relationships, and industry use-cases for Advanced Heaps, Shell Sort, Circular Queue, and Double-Ended Queue (Deque).

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Proposed Changes

1. 🌲 Advanced Heaps Documentation

• File: help_graphs_trees.c
• Description: Renamed the category to "Graphs, Trees & Heaps Help" and added Option 4 covering:
  • Detailed behavioral outlines of D-Ary, Min-Max, Leftist/Skew, Binomial, Fibonacci, and Treap heaps.
  • Relationships: Compares lazy vs. eager merging (Binomial vs. Fibonacci), structure-enforcement tradeoffs (Leftist vs. Skew), and randomized BST balancing (Treap vs. AVL/Red-Black).
  • Use-cases: Maps D-Ary to database external storage, Min-Max to scheduler priority boundaries, and Fibonacci to shortest-path optimizations (Dijkstra/Prim).

2. ⚡ Shell Sort Integration

• File: help_sorting_searching.c
• Description: Added Shell Sort under the $O(N^2)$ sorting submenu:
  • Behavioral outline: A generalization of Insertion Sort using step-by-step gap decreases.
  • Relationships: Compares quadratic performance profiles (Bubble, Selection, Insertion) and positions Shell Sort as a zero-overhead bridge to fast $O(N \log N)$ algorithms.
  • Use-cases: Explains when to select Shell Sort over Quick Sort (e.g. stack limits in embedded systems).

3. 🌀 Circular Queue & Deque (Double-Ended Queue)

• File: help_data_structures.c
• Description: Completed the Stacks & Queues help section by adding:
  • Circular Queue modular wrapping and Deque front/rear access definitions.
  • Relationships: Simple Queue "false overflow" vs. Circular Queue slot reuse, and Deque as a double-ended generalization of both LIFO (Stack) and FIFO (Queue) logic.
  • Use-cases: Maps Circular Queues to streaming ring buffers (audio buffers, CPU scheduling rings) and Deques to work-stealing and history trackers.

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Verification Done

1. Verified compiler syntax checks for all modified files:

   gcc -Wall -Wextra -Werror -std=c11 -c help/help_graphs_trees.c -Ihelp -Isrc/utils
   gcc -Wall -Wextra -Werror -std=c11 -c help/help_sorting_searching.c -Ihelp -Isrc/utils
   gcc -Wall -Wextra -Werror -std=c11 -c help/help_data_structures.c -Ihelp -Isrc/utils

   All files compile cleanly with zero errors/warnings.
2. Verified layout navigation flows locally.

closes #855

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