feat(backfill): implement backfill tool for generating missing embeddings

internal/config/config.go

@@ -17,6 +17,7 @@ type Config struct {
 	Search        SearchConfig        `yaml:"search"`
 	Logging       LoggingConfig       `yaml:"logging"`
 	Observability ObservabilityConfig `yaml:"observability"`
+	Backfill      BackfillConfig      `yaml:"backfill"`
 }
 
 type ServerConfig struct {
@@ -135,3 +136,12 @@ type ObservabilityConfig struct {
 	MetricsEnabled bool `yaml:"metrics_enabled"`
 	PprofEnabled   bool `yaml:"pprof_enabled"`
 }
+
+type BackfillConfig struct {
+	Enabled         bool          `yaml:"enabled"`
+	RunOnStartup    bool          `yaml:"run_on_startup"`
+	Interval        time.Duration `yaml:"interval"`
+	BatchSize       int           `yaml:"batch_size"`
+	MaxPerRun       int           `yaml:"max_per_run"`
+	IncludeArchived bool          `yaml:"include_archived"`
+}