docs: add glossary contributed by Clay Shirky (#80)

Adds comprehensive glossary covering:
- Core principles (MEOW, GUPP, NDI)
- Environments (Town, Rig)
- Roles (Mayor, Deacon, Polecat, Witness, Crew, etc.)
- Work units (Bead, Formula, Molecule, Wisp, Hook)
- Workflow commands (Convoy, Slinging, Nudging, Handoff, Seance, Patrol)

Also adds link to glossary from README Core Concepts section.

Closes #80

Co-Authored-By: Clay Shirky <cshirky@users.noreply.github.com>

README.md

@@ -77,6 +77,8 @@ Work tracking units. Bundle multiple issues/tasks that get assigned to agents.
 
 Git-backed issue tracking system that stores work state as structured data.
 
+> **New to Gas Town?** See the [Glossary](docs/glossary.md) for a complete guide to terminology and concepts.
+
 ## Installation
 
 ### Prerequisites