Implement Pull Request & Issue Templates

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## Problem
The repository currently lacks a standardized way for contributors to describe their changes. This leads to PRs that are difficult to review because they lack context, testing details, or links to related issues.

## Proposed Solution
Create a `.github/` directory and implement standard templates to streamline the contribution process.

## Requirements
* **PR Template:** Create `.github/pull_request_template.md` including:
* Description of changes.
* Type of change (feature, bug fix, docs).
* Checkbox for testing performed.
* Links to relevant issues (e.g., Closes #123).
* **Issue Templates:** Add templates for Bug Reports and Feature Requests to ensure users provide environment details and clear reproduction steps.

## Expected Workflow

```mermaid
graph LR
A[Contributor] -->|Opens PR| B{PR Template Auto-fills}
B --> C[Contributor fills details]
C --> D[Maintainer Review]
D -->|Consistent Info| E[Merge]
```

**Labels:** `documentation`, `DSCWOC'26`, `DSCWOC`

Start by checking the repository root and whether a .github/ directory already exists. Create .github/pull_request_template.md plus Bug Report and Feature Request issue templates covering the listed details, then verify that all requested files and sections are present and match the proposed contributor workflow.

Written by the indexing model from the issue text.