fix(demo): end glucose at yesterday and steady the sleep average

The vitals check holds a day's glucose mean against the band of full
days, so a part day seeded up to the current hour read "below your
range". Spot readings and the CGM stream now end with yesterday.

The aggregate sleep walk drifted to almost nine hours, against which the
~7.5 h per-stage nights read as an hour short. A tighter walk keeps the
trailing average near the nights it is compared with.

scripts/seed-demo.ts

@@ -411,12 +411,15 @@ async function seed() {
     );
     // Body fat: 24% → trending to a healthy ~19%
     const bodyFat = randomWalk(24.0, 19.0, span, 0.4, VALUE_RANGES.BODY_FAT);
-    // Sleep duration in MINUTES (the SLEEP_DURATION unit): ~7h → ~7h45m
+    // Sleep duration in MINUTES (the SLEEP_DURATION unit): ~7h → ~7h40m.
+    // Kept close to the ~7.5 h per-stage nights below, which the start page
+    // holds against this trailing average: a looser walk drifted to almost
+    // nine hours and last night read as "1h 4m less than usual".
     const sleepMin = randomWalk(
       420,
-      465,
+      460,
       span,
-      25,
+      12,
       VALUE_RANGES.SLEEP_DURATION,
     );
     // Steps: 6500 → a solid ~9000
@@ -675,11 +678,14 @@ async function seed() {
       { context: "POSTPRANDIAL", hour: 19, base: 118, jitter: 12 },
       { context: "BEDTIME", hour: 22, base: 99, jitter: 6 },
     ];
-    for (let i = 0; i < span; i++) {
+    // Glucose stops at yesterday. The vitals check compares a day's mean
+    // against the band of full days, so a part day seeded up to the current
+    // hour (fasting and breakfast only) read "below your range", and seeding
+    // the whole day put the afternoon in the future. Yesterday's full day is
+    // what the start page then reads.
+    for (let i = 0; i < span - 1; i++) {
       for (const r of glucoseReadings) {
         const at = daysAgoAt(days - i, r.hour, Math.floor(Math.random() * 30));
-        // Today's later readings are still ahead of the seed's clock.
-        if (at.getTime() > Date.now()) continue;
         const value = Math.round(r.base + (Math.random() - 0.5) * r.jitter);
         await client.query(
           `INSERT INTO measurements (id, user_id, type, value, unit, source, glucose_context, device_type, measured_at, created_at, updated_at)
@@ -706,7 +712,9 @@ async function seed() {
     console.log("Creating continuous glucose (CGM) stream...");
     const cgmDays = 14;
     const cgmStepMin = 15;
-    for (let d = cgmDays - 1; d >= 0; d--) {
+    // The stream ends with yesterday, for the reason given above the spot
+    // readings.
+    for (let d = cgmDays; d >= 1; d--) {
       for (let minute = 0; minute < 24 * 60; minute += cgmStepMin) {
         const hour = minute / 60;
         // Baseline overnight ~90; dawn phenomenon lifts it slightly toward
@@ -720,9 +728,6 @@ async function seed() {
           Math.min(140, Math.max(72, base + (Math.random() - 0.5) * 6)),
         );
         const at = daysAgoAt(d, Math.floor(hour), minute % 60);
-        // Today's stream stops at the seed's own clock: a sensor cannot have
-        // read the evening yet.
-        if (at.getTime() > Date.now()) break;
         const externalId = `cgm-${formatDate(at)}-${minute}`;
         // The measurements_glucose_context_requires_type CHECK requires a
         // non-NULL glucose_context on every BLOOD_GLUCOSE row. A free-running