Part of #401

What

Update the Internal Ecosystem Version Pinning table in DEPENDENCY_MATRIX.md to reflect that network_system has published its first tagged release (v0.1.0).

• Current: network_system row shows "— (no release yet)" and "— (pending first tag)"
• Expected: network_system row shows v0.1.0 for Latest Release, FetchContent GIT_TAG, and vcpkg REF

Why

• The DEPENDENCY_MATRIX.md is the single source of truth for ecosystem version tracking
• network_system v0.1.0 was released on 2026-03-14 but the matrix was not updated
• Downstream consumers referencing this document may not know they can pin to a tagged version

How

Changes Required

1. Update line 165 of DEPENDENCY_MATRIX.md:
   • From: | network_system | — (no release yet) | — (pending first tag) | — (pending first tag) |
   • To: | network_system | \v0.1.0` | `v0.1.0` | `v0.1.0` |`

Acceptance Criteria

• network_system row in DEPENDENCY_MATRIX.md shows v0.1.0
• Verification date on line 170 is updated