Add ISSUES.md: backlog setup for all requirements

[Copilot]

Requirements analysis as Paula (Product Owner) per bots branch instructions. Found 0% issue coverage—17 requirements in requirements.md with no corresponding GitHub issues.

Changes

• ISSUES.md: Complete backlog setup guide containing:
  • Label definitions: requirement IDs (FR-0001–FR-0009, TR-0001–TR-0008), status, priority, type
  • 17 issue templates with DoR/DoD checklists from CONTRIBUTING.md
  • Dependency-ordered implementation sequence
  • GitHub CLI commands for bulk creation
  • Project board column definitions

Issue Template Structure

## Acceptance Criteria
- [ ] Given X, when Y, then Z

## Implementation Guidelines
- Reference to architecture.md choices (AC-xxxx, AG-xxxx)

## Definition of Ready Checklist
- [x] Clear Description
- [ ] Size Estimated
- [ ] Dependencies Identified
...

## Definition of Done Checklist
- [ ] Code Review Passed
- [ ] Tests Written
- [ ] Security Scan Passed
...

Implementation Order

Phase	Requirements	Rationale
1	TR-0001 → TR-0003 → TR-0002	Foundation
2	TR-0004 → FR-0002 → TR-0005	Auth
3	TR-0006 → TR-0007 → FR-0006	Credentials
4+	FR-0001, FR-0003–FR-0009, TR-0008	UI, enhancements

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