docs: Add scope legends to timpani system block diagrams

[LGSI-KarumuriHari]

📋 Description

Enhanced timpani-o and timpani-n system block diagrams in structure.md with visual scope legends and standardized color coding to clearly differentiate project components from external systems.

🎯 Changes Made

1. timpani-o System Block Diagram

• Added Legend with 4 scope categories:

  • 🔵 timpani-o (Our Scope) - Blue (#e3f2fd)
  • 🟢 timpani-n Nodes (Our Scope) - Green (#e8f5e9)
  • 🟠 gRPC Communication (Our Scope) - Orange (#fff3e0)
  • ⚪ External Systems - Gray (#f5f5f5)

• Updated Color Scheme:

  • All timpani-o components now use blue (#e3f2fd) with blue borders
  • timpani-n nodes use green (#e8f5e9) with green borders
  • gRPC Server and Fault Client use orange (#fff3e0) with orange borders
  • External systems (Piccolo, Admin) use gray (#f5f5f5)
  • Legacy D-Bus Server remains gray to indicate deprecated status

2. timpani-n System Block Diagram

• Added Legend with 4 scope categories:

  • 🟢 timpani-n (Our Scope) - Green (#e8f5e9)
  • 🔵 timpani-o (Our Scope) - Blue (#e3f2fd)
  • 🟠 Communication (Our Scope) - Orange (#fff3e0)
  • ⚪ External Systems - Gray (#f5f5f5)

• Updated Color Scheme:

  • All timpani-n internal components use green (#e8f5e9)
  • timpani-o reference uses blue (#e3f2fd)
  • Communication layer (TRPC, DBUS) uses orange (#fff3e0)
  • External systems (Kernel, Sample Apps) use gray (#f5f5f5)

3. Revision History

• Updated to version 0.0c (2026-05-14)
• Comment: "Added scope legends to timpani-o and timpani-n block diagrams"

✅ Verification

• Mermaid syntax validated
• Colors match standard scheme defined in HLD documents
• Legends clearly show all scope categories
• Revision history updated with new version
• Document status remains "Draft"

🔗 Related

Relates to #28

[LGSI-KarumuriHari]

@basheerFZ please review this pr. Thanks

[basheerFZ]

Accepted chnages done as per request