Add streaks, today view, custom plan editing/chapter ranges, and ntfy reminders

Reading plans now track a cross-plan activity log for streaks, surface a
combined "today's reading" view on both Home and the Reading Plans page,
and let custom plans be edited after creation (including narrowing a book
to a specific chapter range). The reader auto-marks a plan's day read after
a dwell period, active plans that fall behind their pace get a "catch me
up" banner, and a new Settings section wires up daily reading reminders
via ntfy.sh, checked once a minute by a small server-side scheduler.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/utils/readingPlans.js

@@ -12,15 +12,28 @@ export const PENTATEUCH = ['GEN', 'EXO', 'LEV', 'NUM', 'DEU'];
 export const WISDOM_BOOKS = ['JOB', 'PSA', 'PRO', 'ECC', 'SNG'];
 
 // Flattens an ordered list of book abbreviations into one chapter-by-chapter list.
-function chaptersFor(bookAbbrevs) {
+// `chapterRanges` (optional) is { [bookAbbrev]: { start, end } } — a custom plan's
+// per-book override to read only part of a book instead of the whole thing.
+function chaptersFor(bookAbbrevs, chapterRanges) {
   const list = [];
   for (const book of bookAbbrevs) {
     const total = CHAPTER_COUNTS[book] ?? 0;
-    for (let chapter = 1; chapter <= total; chapter += 1) list.push({ book, chapter });
+    const range = chapterRanges?.[book];
+    const start = Math.max(1, range?.start ?? 1);
+    const end = Math.min(total, range?.end ?? total);
+    for (let chapter = start; chapter <= end; chapter += 1) list.push({ book, chapter });
   }
   return list;
 }
 
+// Chapter count a book contributes to a plan, honoring a chapter-range override.
+export function bookChapterCount(bookAbbrev, chapterRanges) {
+  const total = CHAPTER_COUNTS[bookAbbrev] ?? 0;
+  const range = chapterRanges?.[bookAbbrev];
+  if (!range) return total;
+  return Math.max(0, Math.min(total, range.end) - Math.max(1, range.start) + 1);
+}
+
 // Splits a flat chapter list into `days` nearly-equal, contiguous slices.
 function distributeIntoDays(chapters, days) {
   const total = chapters.length;
@@ -187,7 +200,7 @@ export function getPlanSchedule(planId) {
   if (scheduleCache.has(planId)) return scheduleCache.get(planId);
   const plan = getPlan(planId);
   if (!plan) return [];
-  const schedule = distributeIntoDays(chaptersFor(plan.books), plan.days);
+  const schedule = distributeIntoDays(chaptersFor(plan.books, plan.chapterRanges), plan.days);
   scheduleCache.set(planId, schedule);
   return schedule;
 }
@@ -233,3 +246,51 @@ export function findDayIndexForRef(schedule, bookAbbrev, chapter) {
   }
   return -1;
 }
+
+// ---------------------------------------------------------------------------
+// Streaks & pace — driven by a plain list of 'YYYY-MM-DD' local-date strings
+// (one per calendar day something was marked read, across all plans).
+// ---------------------------------------------------------------------------
+
+export function localDateString(ts = Date.now()) {
+  const d = new Date(ts);
+  return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`;
+}
+
+// { current, longest } consecutive-calendar-day streak. "current" stays alive
+// through today even if today hasn't been logged yet (so it doesn't drop to 0
+// the moment you wake up) but breaks once a full day is skipped.
+export function computeStreak(activityDates) {
+  if (!activityDates || activityDates.length === 0) return { current: 0, longest: 0 };
+  const daySet = new Set(activityDates);
+  const DAY_MS = 86400000;
+
+  const sorted = Array.from(daySet).sort();
+  let longest = 0;
+  let run = 0;
+  let prevTime = null;
+  for (const ds of sorted) {
+    const t = new Date(`${ds}T00:00:00`).getTime();
+    run = prevTime != null && t - prevTime === DAY_MS ? run + 1 : 1;
+    longest = Math.max(longest, run);
+    prevTime = t;
+  }
+
+  let current = 0;
+  const cursor = new Date();
+  cursor.setHours(0, 0, 0, 0);
+  if (!daySet.has(localDateString(cursor.getTime()))) cursor.setDate(cursor.getDate() - 1);
+  while (daySet.has(localDateString(cursor.getTime()))) {
+    current += 1;
+    cursor.setDate(cursor.getDate() - 1);
+  }
+  return { current, longest };
+}
+
+// How many days a plan's pace has fallen behind, assuming one plan-day per
+// calendar day since it was started. Purely informational — nothing enforces it.
+export function daysBehindPace(plan, progress) {
+  const elapsedDays = Math.floor((Date.now() - progress.startedAt) / 86400000);
+  const expectedDayIndex = Math.min(plan.days - 1, Math.max(0, elapsedDays));
+  return Math.max(0, expectedDayIndex - progress.completedDays.length);
+}