Axum dev server entry point

[aram356]

Description

New trusted-server-adapter-axum crate. Entry point using edgezero_adapter_axum::run_app() with tokio. Construct RuntimeServices with Axum-backed trait implementations. Mock stores for local KV/config/secret. Admin key routes. CI jobs for native target.

Done when

• Route parity + basic-auth gate tests pass
• Admin key routes work
• Axum CI jobs added
• Per-PR gates pass

Blocked by

PR 15

References

• docs/internal/EDGEZERO_MIGRATION.md — Phase 4, PR 16
• Part of EdgeZero migration #480