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/cmd/cycle.go

@@ -30,9 +30,9 @@ var cycleCmd = &cobra.Command{
 
 Session groups:
 - Town sessions: Mayor ↔ Deacon
-- Crew sessions: All crew members in the same rig (e.g., gastown/crew/max ↔ gastown/crew/joe)
+- Crew sessions: All crew members in the same rig (e.g., greenplace/crew/max ↔ greenplace/crew/joe)
 - Rig infra sessions: Witness ↔ Refinery (per rig)
-- Polecat sessions: All polecats in the same rig (e.g., gastown/Toast ↔ gastown/Nux)
+- Polecat sessions: All polecats in the same rig (e.g., greenplace/Toast ↔ greenplace/Nux)
 
 The appropriate cycling is detected automatically from the session name.`,
 }