feat: add WannPassts booking app with Go backend and Vue frontend

Initial project setup for a privacy-focused, self-hosted scheduling app:

- Go backend with JWT auth, SQLite storage, and chi router
- Calendar integrations via Google OAuth (FreeBusy), CalDAV, and ICS links
- Public booking pages with configurable slots and booking requests
- AES-256-GCM encryption for stored provider tokens
- Vue 3 + TypeScript frontend with Vite, Pinia, and Vue Router
- Docs, .gitignore, and .env.example for local development

backend/internal/calendar/ics_test.go

@@ -0,0 +1,145 @@
+package calendar
+
+import (
+	"testing"
+	"time"
+)
+
+const sampleICS = `BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Test//EN
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:STANDARD
+DTSTART:19701025T030000
+TZOFFSETFROM:+0200
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+UID:1
+DTSTART;TZID=Europe/Berlin:20260825T090000
+DTEND;TZID=Europe/Berlin:20260825T100000
+SUMMARY:Zahnarzt
+END:VEVENT
+BEGIN:VEVENT
+UID:2
+DTSTART:20260826T120000Z
+DURATION:PT45M
+SUMMARY:Call
+END:VEVENT
+BEGIN:VEVENT
+UID:3
+DTSTART;VALUE=DATE:20260827
+SUMMARY:Ganztägig
+END:VEVENT
+BEGIN:VEVENT
+UID:4
+DTSTART:20260828T080000Z
+DTEND:20260828T090000Z
+STATUS:CANCELLED
+SUMMARY:Abgesagt
+END:VEVENT
+BEGIN:VEVENT
+UID:5
+DTSTART:20260828T100000Z
+DTEND:20260828T110000Z
+TRANSP:TRANSPARENT
+SUMMARY:Verfügbar
+END:VEVENT
+BEGIN:VEVENT
+UID:6
+DTSTART:20260829T080000Z
+DTEND:202609
+ 01T080000Z
+SUMMARY:Gefaltet
+END:VEVENT
+END:VCALENDAR
+`
+
+func TestParseICS(t *testing.T) {
+	berlin, err := time.LoadLocation("Europe/Berlin")
+	if err != nil {
+		t.Fatal(err)
+	}
+	events := parseICS(sampleICS, berlin)
+	if len(events) != 6 {
+		t.Fatalf("6 Events erwartet, got %d", len(events))
+	}
+
+	// TZID-Event
+	if !events[0].start.Equal(time.Date(2026, 8, 25, 9, 0, 0, 0, berlin)) {
+		t.Errorf("TZID-Start falsch: %v", events[0].start)
+	}
+	if !events[0].end.Equal(time.Date(2026, 8, 25, 10, 0, 0, 0, berlin)) {
+		t.Errorf("TZID-Ende falsch: %v", events[0].end)
+	}
+
+	// UTC + DURATION
+	if !events[1].end.Equal(events[1].start.Add(45*time.Minute)) {
+		t.Errorf("DURATION nicht angewandt: %v", events[1].end)
+	}
+
+	// Ganztägig
+	if !events[2].allDay {
+		t.Error("VALUE=DATE nicht erkannt")
+	}
+
+	// Cancelled / Transparent markiert
+	if !events[3].cancelled {
+		t.Error("CANCELLED nicht erkannt")
+	}
+	if !events[4].transparent {
+		t.Error("TRANSPARENT nicht erkannt")
+	}
+
+	// Gefaltete Zeile (DTEND über zwei Zeilen)
+	if !events[5].end.Equal(time.Date(2026, 9, 1, 8, 0, 0, 0, time.UTC)) {
+		t.Errorf("Folding nicht aufgelöst, Ende: %v", events[5].end)
+	}
+}
+
+func TestParseISODuration(t *testing.T) {
+	cases := map[string]time.Duration{
+		"PT15M":  15 * time.Minute,
+		"PT1H30M": 90 * time.Minute,
+		"P1D":    24 * time.Hour,
+		"P2W":    14 * 24 * time.Hour,
+		"PT45S":  45 * time.Second,
+		"":       0,
+		"X":      0,
+		"P-1D":   0,
+	}
+	for in, want := range cases {
+		got, ok := parseISODuration(in)
+		if in == "" || in == "X" || in == "P-1D" {
+			if ok {
+				t.Errorf("%q sollte ungültig sein", in)
+			}
+			continue
+		}
+		if !ok || got != want {
+			t.Errorf("parseISODuration(%q) = %v (ok=%v), want %v", in, got, ok, want)
+		}
+	}
+}
+
+func TestClampIntervals(t *testing.T) {
+	from := time.Date(2026, 8, 25, 0, 0, 0, 0, time.UTC)
+	to := from.Add(48 * time.Hour)
+	in := []Interval{
+		{Start: from.Add(-2 * time.Hour), End: from.Add(time.Hour)},
+		{Start: from.Add(3 * time.Hour), End: from.Add(2 * time.Hour)}, // ungültig
+		{Start: from.Add(10 * time.Hour), End: to.Add(time.Hour)},
+	}
+	out := clampIntervals(in, from, to)
+	if len(out) != 2 {
+		t.Fatalf("2 Intervalle erwartet, got %d", len(out))
+	}
+	if !out[0].Start.Equal(from) || !out[0].End.Equal(from.Add(time.Hour)) {
+		t.Errorf("Intervall 1 nicht geklemmt: %v–%v", out[0].Start, out[0].End)
+	}
+	if !out[1].End.Equal(to) {
+		t.Errorf("Intervall 2 nicht geklemmt: %v", out[1].End)
+	}
+}