fix(security): escape template outputs and add template security tests

[Viraj0711]

Branch: security/sanitize-templates

Summary

This PR hardens server-side templates against XSS by escaping data injected into HTML and safely serializing values used in JavaScript. It also adds unit tests that render templates with malicious inputs to prevent regressions.

Related Issue

Closes: #355

Type of Change

• Refactor / Security hardening
• Test — adds new security tests

What Was Changed

File	Change made
templates/project.html	Escaped title, meta, description, features, roadmap steps, resources, tech tags. Used tojson for PROJECT_ID. Cleaned class names for badges.
tests/test_security.py	Added test that renders project.html with malicious inputs and asserts content is escaped.
tests/test_index_security.py	Added test that renders index.html with malicious stats and asserts escaping.

How to Test This PR

1. Checkout branch: git checkout security/sanitize-templates
2. Install dependencies: pip install -r requirements.txt
3. Run all tests: python -m pytest -q

Expected test output (relevant lines):

tests/test_security.py .
tests/test_index_security.py .
... (other tests) ...
30 passed in 0.2s

Test Results

(Include CI output or paste results after running locally.)

Self-Review Checklist

• Escaped all template values that render dynamic data.
• Avoided |safe and uncontrolled HTML rendering.
• Serialized JS-injected values safely using tojson.
• Added tests that fail if a future change introduces unescaped output.
• Ran full test suite locally and verified tests pass.

Notes for Reviewer

• Manual review: check places where class names are derived from data (e.g., badge--{{ project.level | lower }}) to ensure they can't break markup — this PR normalizes spaces to hyphens for safety.
• This PR focuses on server-side escaping. Consider follow-ups to: (a) adopt a whitelist sanitizer like bleach if any HTML should be allowed in data fields, and (b) scan client-side code (static/script.js) for unsafe DOM APIs (innerHTML, eval, document.write).

Suggested commit message

fix(security): escape template outputs and add XSS template tests

- Escape dynamic template variables in project and index templates
- Use tojson for safe JS serialization of PROJECT_ID
- Add tests that render templates with malicious inputs

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You can copy-paste the Issue content above into a new GitHub Issue and the PR content into your PR description. If you want, I can also:

• Open the PR for you (push branch and create PR), or
• Add bleach and an example of a sanitized allowlist for fields that require HTML.

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