fix: comprehensive bug fixes and architecture restructuring

Phase 1 — Bug fixes (7 bugs):
- Bug 1: Pulsar mode data loss — always persist to SQLite regardless of mode
- Bug 2: PulsarSend closing TCP client — use independent resetPulsarProducer()
- Bug 3: Greedy regex — use non-greedy (?s)ZCZC.*?NNNN
- Bug 4: Data after NNNN discarded — keep remaining buffer data
- Bug 5: strings.Index > 0 boundary — use strings.Contains
- Bug 6: Variable shadowing in PulsarSend — use = not :=
- Bug 7: Accept failure nil panic — add continue + retry logic

Phase 2 — Architecture restructuring:
- Split utils/ into config/, serial/, telegram/, storage/, transport/
- Define Sender, Repository, Reader interfaces
- Introduce app/ layer with context.Context lifecycle
- Replace spinlock with sync.Mutex
- Unified Config struct replaces 15+ global vars

Phase 3 — Testing & tooling:
- telegram/parser_test.go (7 test cases)
- storage/store_test.go (5 test cases)
- transport/transport_test.go (4 test cases)
- Taskfile: add test, test-race, test-cover tasks
- Go version: 1.15 -> 1.21

cmd/test.go

@@ -47,14 +47,4 @@ func test() {
 
 func init() {
 	rootCmd.AddCommand(testCmd)
-
-	// Here you will define your flags and configuration settings.
-
-	// Cobra supports Persistent Flags which will work for this command
-	// and all subcommands, e.g.:
-	// testCmd.PersistentFlags().String("foo", "", "A help for foo")
-
-	// Cobra supports local flags which will only run when this command
-	// is called directly, e.g.:
-	// testCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
 }