Add build version metadata, changelog, and version display

Embed git commit hash, dirty flag, and target triple in all binaries
via a zero-dependency build.rs. Wire clap short/long version output
so -V shows "0.1.0 (rev abc1234)" and --version adds the target
triple. Log version at daemon startup.

Add version field to show_status control socket API response. Show
the daemon's version in fipstop's tab bar title and Runtime section.

Add CHANGELOG.md in Keep a Changelog format with the 0.1.0-alpha
release (2026-02-24) and unreleased work since then.

src/lib.rs

@@ -3,6 +3,7 @@
 //! A distributed, decentralized network routing protocol for mesh nodes
 //! connecting over arbitrary transports.
 
+pub mod version;
 pub mod bloom;
 pub mod cache;
 pub mod config;