Update installer system for update approval functionality

Major milestone: Update installation system now works
- Implemented unified installer interface with factory pattern
- Created APT, DNF, and Docker installers
- Integrated installer into agent command processing loop
- Update approval button now actually installs packages

Documentation updates:
- Updated claude.md with Session 7 implementation log
- Created clean, professional README.md for GitHub
- Added screenshots section with 4 dashboard views
- Preserved detailed development history in backup files

Repository ready for GitHub alpha release with working installer functionality.

aggregator-server/internal/services/timezone.go

@@ -0,0 +1,58 @@
+package services
+
+import (
+	"time"
+
+	"github.com/aggregator-project/aggregator-server/internal/config"
+)
+
+type TimezoneService struct {
+	config *config.Config
+}
+
+func NewTimezoneService(config *config.Config) *TimezoneService {
+	return &TimezoneService{
+		config: config,
+	}
+}
+
+// GetTimezoneLocation returns the configured timezone as a time.Location
+func (s *TimezoneService) GetTimezoneLocation() (*time.Location, error) {
+	return time.LoadLocation(s.config.Timezone)
+}
+
+// FormatTimeForTimezone formats a time.Time according to the configured timezone
+func (s *TimezoneService) FormatTimeForTimezone(t time.Time) (time.Time, error) {
+	loc, err := s.GetTimezoneLocation()
+	if err != nil {
+		return t, err
+	}
+	return t.In(loc), nil
+}
+
+// GetNowInTimezone returns the current time in the configured timezone
+func (s *TimezoneService) GetNowInTimezone() (time.Time, error) {
+	return s.FormatTimeForTimezone(time.Now())
+}
+
+// GetAvailableTimezones returns a list of common timezones
+func (s *TimezoneService) GetAvailableTimezones() []TimezoneOption {
+	return []TimezoneOption{
+		{Value: "UTC", Label: "UTC (Coordinated Universal Time)"},
+		{Value: "America/New_York", Label: "Eastern Time (ET)"},
+		{Value: "America/Chicago", Label: "Central Time (CT)"},
+		{Value: "America/Denver", Label: "Mountain Time (MT)"},
+		{Value: "America/Los_Angeles", Label: "Pacific Time (PT)"},
+		{Value: "Europe/London", Label: "London (GMT)"},
+		{Value: "Europe/Paris", Label: "Paris (CET)"},
+		{Value: "Europe/Berlin", Label: "Berlin (CET)"},
+		{Value: "Asia/Tokyo", Label: "Tokyo (JST)"},
+		{Value: "Asia/Shanghai", Label: "Shanghai (CST)"},
+		{Value: "Australia/Sydney", Label: "Sydney (AEDT)"},
+	}
+}
+
+type TimezoneOption struct {
+	Value string `json:"value"`
+	Label string `json:"label"`
+}