Remove keepalive file infrastructure for feed-based wake model (gt-vdprb.2)

- Remove TouchTownActivity() calls from root.go PersistentPreRun hook
- Remove ReadTownActivity() and activity-based backoff from daemon.go
- Delete TouchTownActivity/ReadTownActivity functions from keepalive.go
- Replace dynamic backoff with fixed 10-min recovery heartbeat

Normal wake is now handled by feed subscription (bd activity --follow).
The daemon is a safety net for dead sessions, GUPP violations, and orphaned work.

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

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

internal/cmd/root.go

@@ -6,7 +6,6 @@ import (
 	"strings"
 
 	"github.com/spf13/cobra"
-	"github.com/steveyegge/gastown/internal/keepalive"
 )
 
 var rootCmd = &cobra.Command{
@@ -17,16 +16,6 @@ var rootCmd = &cobra.Command{
 
 It coordinates agent spawning, work distribution, and communication
 across distributed teams of AI agents working on shared codebases.`,
-	PersistentPreRun: func(cmd *cobra.Command, args []string) {
-		// Signal agent activity by touching keepalive file
-		// Build command path: gt status, gt mail send, etc.
-		cmdPath := buildCommandPath(cmd)
-		keepalive.TouchWithArgs(cmdPath, args)
-
-		// Also signal town-level activity for daemon exponential backoff
-		// This resets the backoff when any gt command runs
-		keepalive.TouchTownActivity(cmdPath)
-	},
 }
 
 // Execute runs the root command and returns an exit code.