feat(17-05): implement serve and schedule commands replacing stubs

- cmd/serve.go: starts scheduler, optionally starts Telegram bot with --telegram flag
- cmd/schedule.go: add/list/remove/run subcommands for scheduled scan job CRUD
- pkg/scheduler/: gocron v2 based scheduler with DB-backed jobs and scan execution
- pkg/storage/scheduled_jobs.go: scheduled_jobs table CRUD with tests
- Remove serve and schedule stubs from cmd/stubs.go

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/storage/scheduled_jobs.go

@@ -0,0 +1,164 @@
+package storage
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+// ScheduledJob represents a cron-based recurring scan job.
+type ScheduledJob struct {
+	ID        int64
+	Name      string
+	CronExpr  string
+	ScanPath  string
+	Enabled   bool
+	Notify    bool
+	LastRunAt *time.Time
+	NextRunAt *time.Time
+	CreatedAt time.Time
+}
+
+// SaveScheduledJob inserts a new scheduled job and returns its ID.
+func (db *DB) SaveScheduledJob(job ScheduledJob) (int64, error) {
+	enabledInt := 0
+	if job.Enabled {
+		enabledInt = 1
+	}
+	notifyInt := 0
+	if job.Notify {
+		notifyInt = 1
+	}
+
+	res, err := db.sql.Exec(
+		`INSERT INTO scheduled_jobs (name, cron_expr, scan_path, enabled, notify)
+		 VALUES (?, ?, ?, ?, ?)`,
+		job.Name, job.CronExpr, job.ScanPath, enabledInt, notifyInt,
+	)
+	if err != nil {
+		return 0, fmt.Errorf("inserting scheduled job: %w", err)
+	}
+	return res.LastInsertId()
+}
+
+// ListScheduledJobs returns all scheduled jobs ordered by creation time.
+func (db *DB) ListScheduledJobs() ([]ScheduledJob, error) {
+	rows, err := db.sql.Query(
+		`SELECT id, name, cron_expr, scan_path, enabled, notify, last_run_at, next_run_at, created_at
+		 FROM scheduled_jobs ORDER BY created_at ASC`,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("querying scheduled jobs: %w", err)
+	}
+	defer rows.Close()
+
+	var jobs []ScheduledJob
+	for rows.Next() {
+		j, err := scanJobRow(rows)
+		if err != nil {
+			return nil, err
+		}
+		jobs = append(jobs, j)
+	}
+	return jobs, rows.Err()
+}
+
+// GetScheduledJob returns a single job by ID.
+func (db *DB) GetScheduledJob(id int64) (*ScheduledJob, error) {
+	row := db.sql.QueryRow(
+		`SELECT id, name, cron_expr, scan_path, enabled, notify, last_run_at, next_run_at, created_at
+		 FROM scheduled_jobs WHERE id = ?`, id,
+	)
+	var j ScheduledJob
+	var enabledInt, notifyInt int
+	var lastRun, nextRun, createdAt sql.NullString
+	if err := row.Scan(&j.ID, &j.Name, &j.CronExpr, &j.ScanPath,
+		&enabledInt, &notifyInt, &lastRun, &nextRun, &createdAt); err != nil {
+		return nil, err
+	}
+	j.Enabled = enabledInt != 0
+	j.Notify = notifyInt != 0
+	j.LastRunAt = parseNullTime(lastRun)
+	j.NextRunAt = parseNullTime(nextRun)
+	if createdAt.Valid {
+		t, _ := time.Parse("2006-01-02 15:04:05", createdAt.String)
+		j.CreatedAt = t
+	}
+	return &j, nil
+}
+
+// DeleteScheduledJob removes a job by ID and returns rows affected.
+func (db *DB) DeleteScheduledJob(id int64) (int64, error) {
+	res, err := db.sql.Exec(`DELETE FROM scheduled_jobs WHERE id = ?`, id)
+	if err != nil {
+		return 0, fmt.Errorf("deleting scheduled job %d: %w", id, err)
+	}
+	return res.RowsAffected()
+}
+
+// UpdateJobLastRun updates the last_run_at timestamp for a job.
+func (db *DB) UpdateJobLastRun(id int64, t time.Time) error {
+	_, err := db.sql.Exec(
+		`UPDATE scheduled_jobs SET last_run_at = ? WHERE id = ?`,
+		t.Format("2006-01-02 15:04:05"), id,
+	)
+	return err
+}
+
+// ListEnabledScheduledJobs returns only enabled jobs.
+func (db *DB) ListEnabledScheduledJobs() ([]ScheduledJob, error) {
+	rows, err := db.sql.Query(
+		`SELECT id, name, cron_expr, scan_path, enabled, notify, last_run_at, next_run_at, created_at
+		 FROM scheduled_jobs WHERE enabled = 1 ORDER BY created_at ASC`,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("querying enabled scheduled jobs: %w", err)
+	}
+	defer rows.Close()
+
+	var jobs []ScheduledJob
+	for rows.Next() {
+		j, err := scanJobRow(rows)
+		if err != nil {
+			return nil, err
+		}
+		jobs = append(jobs, j)
+	}
+	return jobs, rows.Err()
+}
+
+func scanJobRow(rows *sql.Rows) (ScheduledJob, error) {
+	var j ScheduledJob
+	var enabledInt, notifyInt int
+	var lastRun, nextRun, createdAt sql.NullString
+	if err := rows.Scan(&j.ID, &j.Name, &j.CronExpr, &j.ScanPath,
+		&enabledInt, &notifyInt, &lastRun, &nextRun, &createdAt); err != nil {
+		return j, fmt.Errorf("scanning scheduled job row: %w", err)
+	}
+	j.Enabled = enabledInt != 0
+	j.Notify = notifyInt != 0
+	j.LastRunAt = parseNullTime(lastRun)
+	j.NextRunAt = parseNullTime(nextRun)
+	if createdAt.Valid {
+		t, _ := time.Parse("2006-01-02 15:04:05", createdAt.String)
+		j.CreatedAt = t
+	}
+	return j, nil
+}
+
+func parseNullTime(ns sql.NullString) *time.Time {
+	if !ns.Valid || ns.String == "" {
+		return nil
+	}
+	// Try multiple formats SQLite may return.
+	for _, layout := range []string{
+		"2006-01-02 15:04:05",
+		"2006-01-02T15:04:05Z",
+		time.RFC3339,
+	} {
+		if t, err := time.Parse(layout, ns.String); err == nil {
+			return &t
+		}
+	}
+	return nil
+}