Replace 'gastown' with 'greenplace' in user-facing docs/examples

Using "greenplace" (The Green Place from Mad Max: Fury Road) as the
canonical example project/rig name in documentation and help text.
This provides a clearer distinction from the actual gastown repo name.

Changes:
- docs/*.md: Updated all example paths and commands
- internal/cmd/*.go: Updated help text examples
- internal/templates/: Updated example references
- Tests: Updated to use greenplace in example session names

Note: Import paths (github.com/steveyegge/gastown) and actual code
paths referencing the gastown repo structure are unchanged.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/templates/roles/refinery.md.tmpl

@@ -115,7 +115,7 @@ git status                    # See what conflicted
 # DECISION: Can I resolve it? Is it trivial?
 #   - If trivial: fix, git add, git rebase --continue
 #   - If complex: git rebase --abort, notify polecat
-gt mail send gastown/polecats/rictus -s "Rebase needed" -m "..."
+gt mail send greenplace/polecats/rictus -s "Rebase needed" -m "..."
 ```
 
 ## Patrol Molecule: mol-refinery-patrol

internal/templates/templates.go

@@ -20,7 +20,7 @@ type Templates struct {
 // RoleData contains information for rendering role contexts.
 type RoleData struct {
 	Role        string   // mayor, witness, refinery, polecat, crew, deacon
-	RigName     string   // e.g., "gastown"
+	RigName     string   // e.g., "greenplace"
 	TownRoot    string   // e.g., "/Users/steve/ai"
 	WorkDir     string   // current working directory
 	Polecat     string   // polecat name (for polecat role)