Add GitHub issue templates with Reservations and Exclusions feature request

[Copilot]

Adds GitHub issue templates to the repository, including a detailed feature request for IP address space management capabilities.

Changes

• .github/ISSUE_TEMPLATE/reservations-and-exclusions.md - Feature request documenting:

  • Exclusions: CIDR ranges to block (S2S VPNs, on-prem, partner networks) with conflict detection
  • Reservations: Reserve address spaces for future VNET deployments with state tracking
  • Proposed API endpoints, UI mockups, acceptance criteria, phased rollout plan

• .github/ISSUE_TEMPLATE/feature_request.md - Generic feature request template

• .github/ISSUE_TEMPLATE/bug_report.md - Bug report template

Proposed Address Space Visualization

┌────────────────────────────────────────┐
│  Address Space Overview                │
├────────────────────────────────────────┤
│  🟢 Free:        10.0.0.0/8  (65%)    │
│  🔵 Deployed:    10.50.0.0/12 (25%)   │
│  🟡 Reserved:    10.100.0.0/14 (7%)   │
│  ⚫ Excluded:    192.168.0.0/16 (3%)  │
└────────────────────────────────────────┘

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