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/molecule.go

@@ -135,9 +135,9 @@ Output includes:
 - Next action hint
 
 Examples:
-  gt mol status                    # Show current agent's hook
-  gt mol status gastown/nux        # Show specific polecat's hook
-  gt mol status gastown/witness    # Show witness's hook`,
+  gt mol status                       # Show current agent's hook
+  gt mol status greenplace/nux        # Show specific polecat's hook
+  gt mol status greenplace/witness    # Show witness's hook`,
 	Args: cobra.MaximumNArgs(1),
 	RunE: runMoleculeStatus,
 }
@@ -159,10 +159,10 @@ Output includes:
 - Current step that should be worked on next
 
 Examples:
-  gt molecule current              # Current agent's work
-  gt molecule current gastown/furiosa
+  gt molecule current                 # Current agent's work
+  gt molecule current greenplace/furiosa
   gt molecule current deacon
-  gt mol current gastown/witness`,
+  gt mol current greenplace/witness`,
 	Args: cobra.MaximumNArgs(1),
 	RunE: runMoleculeCurrent,
 }