feat: Add GitHub project management infrastructure (RACI, issue templates, workflows)

[Copilot]

The repository had 224+ open issues with no structured intake, no defined contribution process, and no automated triage — making it hard for contributors and maintainers to track, prioritize, and report progress at scale.

Issue Templates (.github/ISSUE_TEMPLATE/)

• Three structured YAML forms: Bug Report, Content Update, Feature Request — replace free-form issue creation with required fields (affected URL, type, source reference, amendment status)
• config.yml disables blank issues; surfaces Discord and feedback contact links

Pull Request Template (.github/PULL_REQUEST_TEMPLATE.md)

• RACI confirmation table — every PR author explicitly acknowledges their R/A/C/I role
• Separate author and reviewer checklists; requires a linked issue

CODEOWNERS (.github/CODEOWNERS)

• @XRPLF/docs-maintainers assigned across all paths — enforces at least one human approval before merge when combined with branch protection rules (setup documented in RACI.md)

Workflows (.github/workflows/)

Workflow	Trigger	What it does
stale.yml	Daily	Issues → stale at 90d, closed at 104d; PRs → stale at 30d, closed at 37d
auto-label.yml	PR open/sync	Labels PRs by changed file paths via actions/labeler@v5 + labeler.yml
issue-triage.yml	Issue opened	Keyword → label mapping; unmatched issues get needs triage + a comment
pr-check.yml	PR open/edit	Validates non-trivial description, linked issue, RACI checklist; posts/updates a bot comment; fails check on hard errors for non-draft PRs
greet-contributor.yml	First issue/PR	Posts onboarding guidance to first-time contributors

RACI Documentation (.github/project-management/RACI.md)

• Role definitions mapped to GitHub primitives (contributor → R, CODEOWNERS → A, tagged SMEs → C, watchers/linked issues → I)
• Per-activity RACI table, project board column definitions + automation rules, branch protection checklist, labels reference

CONTRIBUTING.md

• Added Quick Start, RACI summary, and workflow table — replaces the single external link that previously comprised the entire file

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