Show ages on the AS and prefix pages in words (closes #163)

The Age column printed Go's duration format for every plural age, such
as "5m0s ago" or "360h0m0s ago".

The templates now register humanize.Time from go-humanize, which the
server already uses, as the timeSince function, and the hand-written
function is gone. Ages read "5 minutes ago", "3 hours ago" or "2 weeks
ago". An age under a minute reads "now" or in seconds instead of "just
now". An age over a month reads in months or years instead of a date.

Model: opus-5-5

internal/templates/templates.go

@@ -7,9 +7,9 @@ import (
 	"net/url"
 	"strings"
 	"sync"
-	"time"
 
 	"git.eeqj.de/sneak/routewatch/internal/version"
+	"github.com/dustin/go-humanize"
 )
 
 //go:embed index.html
@@ -48,48 +48,7 @@ var (
 	once sync.Once
 )
 
-const (
-	hoursPerDay   = 24
-	daysPerMonth  = 30
-	cidrPartCount = 2 // A CIDR has two parts: prefix and length
-)
-
-// timeSince returns a human-readable duration since the given time
-func timeSince(t time.Time) string {
-	duration := time.Since(t)
-	if duration < time.Minute {
-		return "just now"
-	}
-
-	if duration < time.Hour {
-		minutes := int(duration.Minutes())
-		if minutes == 1 {
-			return "1 minute ago"
-		}
-
-		return duration.Truncate(time.Minute).String() + " ago"
-	}
-
-	if duration < hoursPerDay*time.Hour {
-		hours := int(duration.Hours())
-		if hours == 1 {
-			return "1 hour ago"
-		}
-
-		return duration.Truncate(time.Hour).String() + " ago"
-	}
-
-	days := int(duration.Hours() / hoursPerDay)
-	if days == 1 {
-		return "1 day ago"
-	}
-
-	if days < daysPerMonth {
-		return duration.Truncate(hoursPerDay*time.Hour).String() + " ago"
-	}
-
-	return t.Format("2006-01-02")
-}
+const cidrPartCount = 2 // A CIDR has two parts: prefix and length
 
 // prefixURL generates a URL path for a prefix in CIDR notation.
 // Takes a prefix like "192.168.1.0/24" and returns "/prefix/192.168.1.0/24"
@@ -113,7 +72,7 @@ func initTemplates() {
 
 	// Create common template functions
 	funcs := template.FuncMap{
-		"timeSince":       timeSince,
+		"timeSince":       humanize.Time,
 		"urlEncode":       url.QueryEscape,
 		"prefixURL":       prefixURL,
 		"appName":         func() string { return version.Name },