[WIP] example: add python examples

[LHT129]

Summary by Sourcery

Add standalone Python example scripts for HNSW, HGraph, and brute-force indexes and remove the old placeholder examples.

New Features:

• Provide a Python example demonstrating HNSW index creation, building, and k-NN search.
• Provide a Python example demonstrating HGraph index creation, building, and k-NN search.
• Provide a Python example demonstrating brute-force index creation, building, and k-NN search.

Chores:

• Remove deprecated placeholder scripts from the todo_examples directory.

[sourcery-ai]

Reviewer's Guide

This PR migrates working Python example scripts for HNSW, HGraph, and brute-force indices into the main examples directory with full create/build/search demos, cleans up the legacy todo_examples placeholders, and applies a minor formatting fix to the diskann example license header.

Sequence diagram for index creation, build, and search in Python examples

sequenceDiagram
    actor User
    participant Script
    participant pyvsag
    User->>Script: Run example script
    Script->>pyvsag: Create Index (type, params)
    Script->>pyvsag: Build Index (vectors, ids, num_elements, dim)
    Script->>pyvsag: knn_search(vector, k, parameters)
    pyvsag-->>Script: Return result_ids, result_dists
    Script->>User: Print results

Loading

File-Level Changes

Change	Details	Files
Add complete Python example scripts for various index types	Demonstrate dataset generation and ID assignment with numpy Showcase index creation with pyvsag.Index for each algorithm Illustrate building and querying (knn_search) flow with parameters Include Apache-2.0 license header in each example	examples/python/101_index_hnsw.py examples/python/103_index_hgraph.py examples/python/105_index_brute_force.py
Remove outdated placeholder scripts	Delete stub example files for indices 101, 103, and 105 in todo_examples	examples/python/todo_examples/101_index_hnsw.py examples/python/todo_examples/103_index_hgraph.py examples/python/todo_examples/105_index_brute_force.py
Fix license formatting in diskann example	Ensure newline at end of file to comply with formatting standards	examples/python/todo_examples/102_index_diskann.py

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main    #1190      +/-   ##
==========================================
- Coverage   91.88%   91.82%   -0.06%     
==========================================
  Files         312      312              
  Lines       18682    18682              
==========================================
- Hits        17166    17155      -11     
- Misses       1516     1527      +11     

Flag	Coverage Δ
cpp	91.82% <ø> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
common	91.57% <ø> (ø)
datacell	92.69% <ø> (+0.32%)	⬆️
index	90.41% <ø> (-0.44%)	⬇️
simd	100.00% <ø> (ø)

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