fix: correct policy-enforcement.yml path and scaffold required repo structure

[mr-adonis-jimenez]

Summary

Fixes two issues causing Validate Repository Structure workflow failures:

1. Move policy-enforcement.yml to correct path

• Removed the file from the nested .github/workflows/.github/workflows/ path (GitHub Actions ignores it there)
• Re-created it at the correct .github/workflows/policy-enforcement.yml path

2. Scaffold missing required directories and files

The validate-repo-structure.yml workflow enforces the presence of these — all were missing:

Directories:

• model/ — financial model assets
• docs/ — documentation
• scripts/ — automation scripts
• data/ — data files
• screenshots/ — UI/output screenshots

Documentation files:

• docs/METHODOLOGY.md
• docs/ASSUMPTIONS.md
• CONTRIBUTING.md

All scaffold files are stubs ready to be filled in.

[gemini-code-assist]

Code Review

This pull request establishes the project's foundational structure by introducing a contribution guide, documentation templates, and necessary directory placeholders. The review feedback suggests improving the clarity of the branch naming instructions with a concrete example and notes that a referenced image in the README is missing from the new screenshots directory, which would result in a broken link.

[gemini-code-assist]

To improve clarity for new contributors, it would be helpful to provide a full example of a branch name here. The current text only lists the prefixes, which might be slightly ambiguous.

Suggested change

	2. Create a branch following the naming convention: `feature/`, `bugfix/`, `hotfix/`, or `chore/`
	2. Create a branch following the naming convention detailed below (e.g., `feature/add-new-button`).

[gemini-code-assist]

The README.md file references an image at screenshots/dashboard-overview.png. Since this PR creates the screenshots directory but does not add the image, the link in the README.md will be broken. Please consider adding a placeholder image or commenting out the image link in README.md to avoid this.