chore: bump version to 0.5.1

v0.5.0 tag is permanently registered (immutable release) even though
the release was deleted. Bump to v0.5.1 for the corrected release.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: timeleft--

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "fava-trails"
-version = "0.5.0"
+version = "0.5.1"
 description = "FAVA Trails 🫛👣 — Federated Agents Versioned Audit Trail. VCS-backed memory for AI agents via MCP."
 readme = "README.md"
 requires-python = ">=3.11"