[ci skip] Flatten module wrappers into stack roots

Remove the module "xxx" { source = "./module" } indirection layer
from all 66 service stacks. Resources are now defined directly in
each stack's main.tf instead of through a wrapper module.

- Merge module/main.tf contents into stack main.tf
- Apply variable replacements (var.tier -> local.tiers.X, renamed vars)
- Fix shared module paths (one fewer ../ at each level)
- Move extra files/dirs (factory/, chart_values, subdirs) to stack root
- Update state files to strip module.<name>. prefix
- Update CLAUDE.md to reflect flat structure

Verified: terragrunt plan shows 0 add, 0 destroy across all stacks.

stacks/f1-stream/files/internal/store/store.go

@@ -0,0 +1,53 @@
+package store
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+type Store struct {
+	dir         string
+	streamsMu   sync.RWMutex
+	usersMu     sync.RWMutex
+	scrapedMu   sync.RWMutex
+	sessionsMu  sync.RWMutex
+	healthMu    sync.RWMutex
+}
+
+func New(dir string) (*Store, error) {
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return nil, err
+	}
+	return &Store{dir: dir}, nil
+}
+
+func (s *Store) filePath(name string) string {
+	return filepath.Join(s.dir, name)
+}
+
+// readJSON reads a JSON file into the target. Returns nil if file doesn't exist.
+func readJSON(path string, target interface{}) error {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	return json.Unmarshal(data, target)
+}
+
+// writeJSON atomically writes target as JSON to path using temp-file-then-rename.
+func writeJSON(path string, data interface{}) error {
+	b, err := json.MarshalIndent(data, "", "  ")
+	if err != nil {
+		return err
+	}
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, b, 0644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, path)
+}