fix: remove vestigial state.json files from agent directories

Agent directories (witness/, refinery/, mayor/) contained state.json files
with last_active timestamps that were never updated, making them stale and
misleading. This change removes:

- initAgentStates function that created vestigial state.json files
- AgentState type and related Load/Save functions from config package
- MayorStateValidCheck from doctor checks
- requesting_* lifecycle verification (dead code - flags were never set)
- FileStateJSON constant and MayorStatePath function

Kept intact:
- daemon/state.json (actively used for daemon runtime state)
- crew/<name>/state.json (operational CrewWorker metadata)
- Agent state tracking via beads (the ZFC-compliant approach)

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

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

internal/cmd/rig_integration_test.go

@@ -542,17 +542,20 @@ func TestRigAddCreatesAgentDirs(t *testing.T) {
 
 	rigPath := filepath.Join(townRoot, "agenttest")
 
-	// Verify agent state files exist
-	expectedStateFiles := []string{
-		"witness/state.json",
-		"refinery/state.json",
-		"mayor/state.json",
+	// Verify agent directories exist (state.json files are no longer created)
+	expectedDirs := []string{
+		"witness",
+		"refinery",
+		"mayor",
 	}
 
-	for _, stateFile := range expectedStateFiles {
-		path := filepath.Join(rigPath, stateFile)
-		if _, err := os.Stat(path); err != nil {
-			t.Errorf("expected state file %s to exist: %v", stateFile, err)
+	for _, dir := range expectedDirs {
+		path := filepath.Join(rigPath, dir)
+		info, err := os.Stat(path)
+		if err != nil {
+			t.Errorf("expected directory %s to exist: %v", dir, err)
+		} else if !info.IsDir() {
+			t.Errorf("expected %s to be a directory", dir)
 		}
 	}
 }