Improvements to fitness page

- Data now comes from a calendar
- Hovering in charts shows day info
- Optical enhancements to chart rendering
- Allow setting/showing goal weight
- Allow toggeling between absolute and zoomed in weight axis

fitness_test.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"os"
+	"strings"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestFitnessWeights(t *testing.T) {
+	withBerlin(t)
+	dir := t.TempDir()
+	prev := calendarsDir
+	calendarsDir = dir
+	t.Cleanup(func() { calendarsDir = prev })
+
+	if err := os.WriteFile(filepath.Join(dir, ".page-settings"),
+		[]byte("type = calendars\nweight = Gewicht\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	writeCal(t, dir, "Gewicht",
+		`UID:1
+		SUMMARY:96 kg
+		DTSTART;VALUE=DATE:20261001`,
+		`UID:2
+		SUMMARY:95,6kg
+		DTSTART;VALUE=DATE:20261003`,
+		`UID:3
+		SUMMARY:not a weight
+		DTSTART;VALUE=DATE:20261004`,
+		`UID:4
+		SUMMARY:90 kg
+		DTSTART;VALUE=DATE:20261010`,
+	)
+
+	today := time.Date(2026, 10, 5, 0, 0, 0, 0, time.UTC)
+	got := fitnessWeights(today)
+	want := []weightPoint{
+		{date: time.Date(2026, 10, 1, 0, 0, 0, 0, time.UTC), value: 96},
+		{date: time.Date(2026, 10, 3, 0, 0, 0, 0, time.UTC), value: 95.6},
+	}
+	if len(got) != len(want) {
+		t.Fatalf("got %+v, want %+v", got, want)
+	}
+	for i := range want {
+		if !got[i].date.Equal(want[i].date) || got[i].value != want[i].value {
+			t.Fatalf("point %d: got %+v, want %+v", i, got[i], want[i])
+		}
+	}
+}
+
+func TestTimeXTicks(t *testing.T) {
+	d := func(y int, m time.Month, day int) time.Time { return time.Date(y, m, day, 0, 0, 0, 0, time.UTC) }
+	for _, c := range []struct {
+		from, to time.Time
+		want     string
+	}{
+		{d(2022, 11, 28), d(2026, 9, 21), "2023 2024 2025 2026"},
+		{d(2025, 9, 27), d(2026, 9, 27), "Oct 2025|Jan 2026|Apr|Jul"},
+		{d(2026, 6, 27), d(2026, 9, 27), "Jul 2026|Aug|Sep"},
+		{d(2026, 8, 27), d(2026, 9, 27), "31 Aug|7 Sep|14 Sep|21 Sep"},
+	} {
+		var got []string
+		for _, tk := range timeXTicks(chartScale{x0: c.from, x1: c.to}) {
+			got = append(got, tk.Label)
+		}
+		sep := " "
+		if strings.Contains(c.want, "|") {
+			sep = "|"
+		}
+		if g := strings.Join(got, sep); g != c.want {
+			t.Errorf("%s..%s: got %q, want %q", c.from.Format("2006-01-02"), c.to.Format("2006-01-02"), g, c.want)
+		}
+	}
+}