Refactor startup paths to use RuntimeConfig (gt-j0546)

Replaced all hardcoded 'claude --dangerously-skip-permissions' invocations
with configurable helpers from internal/config:

- GetRuntimeCommand(rigPath) - simple command string
- GetRuntimeCommandWithPrompt(rigPath, prompt) - with initial prompt
- BuildAgentStartupCommand(role, bdActor, rigPath, prompt) - generic agent
- BuildPolecatStartupCommand(rigName, polecatName, rigPath, prompt) - polecat
- BuildCrewStartupCommand(rigName, crewName, rigPath, prompt) - crew
- BuildStartupCommand(envVars, rigPath, prompt) - custom env vars

Files updated:
- internal/cmd/start.go (4 locations)
- internal/cmd/crew_lifecycle.go (2 locations)
- internal/cmd/crew_at.go (2 locations)
- internal/cmd/deacon.go
- internal/cmd/witness.go
- internal/cmd/up.go (2 locations)
- internal/cmd/handoff.go (2 locations)
- internal/daemon/daemon.go (3 locations)
- internal/daemon/lifecycle.go
- internal/session/manager.go
- internal/refinery/manager.go
- internal/boot/boot.go

This enables future support for alternative LLM runtimes (aider, etc.)
via rig/town settings configuration.

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

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

internal/session/manager.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/steveyegge/gastown/internal/claude"
+	"github.com/steveyegge/gastown/internal/config"
 	"github.com/steveyegge/gastown/internal/constants"
 	"github.com/steveyegge/gastown/internal/rig"
 	"github.com/steveyegge/gastown/internal/tmux"
@@ -178,9 +179,7 @@ func (m *Manager) Start(polecat string, opts StartOptions) error {
 	if command == "" {
 		// Polecats run with full permissions - Gas Town is for grownups
 		// Export env vars inline so Claude's role detection works
-		bdActor := fmt.Sprintf("%s/polecats/%s", m.rig.Name, polecat)
-		command = fmt.Sprintf("export GT_ROLE=polecat GT_RIG=%s GT_POLECAT=%s BD_ACTOR=%s GIT_AUTHOR_NAME=%s && claude --dangerously-skip-permissions",
-			m.rig.Name, polecat, bdActor, bdActor)
+		command = config.BuildPolecatStartupCommand(m.rig.Name, polecat, m.rig.Path, "")
 	}
 	if err := m.tmux.SendKeys(sessionID, command); err != nil {
 		return fmt.Errorf("sending command: %w", err)