governance: Add CONTRIBUTING.md, branch naming guide, and GitHub issue templates (bug + feature)

[Sir-Emress]

Problem

BOS has no CONTRIBUTING.md, no branch naming conventions, and no GitHub issue templates.
Without these, contributors submit inconsistent PRs, open vague issues, and maintainers
spend extra time clarifying basic expectations.

Proposed Solution

1. Create CONTRIBUTING.md with:

   • Code of conduct
   • Fork and clone workflow
   • Branch naming conventions: docs/, fix/, governance/, chore/
   • Commit message format (Conventional Commits: docs(readme): add project overview)
   • Pull request process: issue linking with Closes #<number>, size guidance, review expectations
   • Issue reporting guidelines

2. Create .github/ISSUE_TEMPLATE/bug_report.md with fields:

   • Description, steps to reproduce, expected vs actual behaviour, environment

3. Create .github/ISSUE_TEMPLATE/feature_request.md with fields:

   • Problem statement, proposed solution, alternatives considered, acceptance criteria

Why It Matters

Governance infrastructure is one of the strongest predictors of whether a community
project stays healthy over time. Standardized templates and contribution guides help
maintainers receive better-quality work and give contributors clear expectations.

Acceptance Criteria

• CONTRIBUTING.md covers: CoC, workflow, branch naming, commit style, PR process, issue guidelines
• Bug report template exists with required fields
• Feature request template exists with required fields
• CONTRIBUTING.md is linked from README.md