chore(analytics): drop unreferenced movingAverage and weeklyAverages exports

Neither function had any production caller. The chart components in
src/components/charts/* implement a local movingAverageByPoints rather
than reaching for the lib helper, and weeklyAverages was never imported
outside its own test file. detectAnomalies stays — it is reached
transitively through summarize() which the analytics, insights, and
measurements-series routes all consume.

src/lib/analytics/__tests__/correlations.test.ts

@@ -1,10 +1,6 @@
 import { describe, it, expect } from "vitest";
 import type { DataPoint } from "../trends";
-import {
-  pairByTimestamp,
-  pearsonCorrelation,
-  weeklyAverages,
-} from "../correlations";
+import { pairByTimestamp, pearsonCorrelation } from "../correlations";
 
 function makePoints(values: number[], startDaysAgo = 30): DataPoint[] {
   const now = Date.now();
@@ -107,57 +103,3 @@ describe("pearsonCorrelation", () => {
   });
 });
 
-describe("weeklyAverages", () => {
-  it("returns empty for empty input", () => {
-    expect(weeklyAverages([])).toEqual([]);
-  });
-
-  it("groups data points by ISO week", () => {
-    const data = makePoints(
-      [70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83],
-      14,
-    );
-    const result = weeklyAverages(data);
-    // 14 days = 2-3 weeks
-    expect(result.length).toBeGreaterThanOrEqual(2);
-    expect(result.length).toBeLessThanOrEqual(3);
-  });
-
-  it("averages values within same week", () => {
-    const now = new Date();
-    // Find the Monday of current week
-    const day = now.getDay();
-    const monday = new Date(now);
-    monday.setDate(now.getDate() - day + (day === 0 ? -6 : 1));
-    monday.setHours(12, 0, 0, 0);
-
-    const tuesday = new Date(monday);
-    tuesday.setDate(monday.getDate() + 1);
-
-    const data: DataPoint[] = [
-      { date: monday, value: 70 },
-      { date: tuesday, value: 80 },
-    ];
-    const result = weeklyAverages(data);
-    expect(result).toHaveLength(1);
-    expect(result[0].value).toBe(75);
-  });
-
-  // v3 audit caught a TZ bug: a Sunday-evening Berlin reading (e.g. 22:00
-  // local = 21:00 UTC in summer / 21:00 UTC in winter via DST) bucketed
-  // into next week on UTC servers because `Date.getDay()` was system-local.
-  // The Berlin-TZ-aware implementation puts the same point into THIS week.
-  it("buckets Sunday-evening Berlin into the same ISO week as the preceding Monday", () => {
-    // 2024-08-04 is a Sunday; 22:00 Berlin = 20:00 UTC (CEST). The Monday
-    // of the same Berlin week is 2024-07-29.
-    const sundayEveningBerlin = new Date("2024-08-04T20:00:00.000Z");
-    const mondayMidday = new Date("2024-07-29T11:00:00.000Z");
-    const result = weeklyAverages([
-      { date: mondayMidday, value: 70 },
-      { date: sundayEveningBerlin, value: 90 },
-    ]);
-    expect(result).toHaveLength(1);
-    expect(result[0].value).toBe(80); // (70 + 90) / 2
-    expect(result[0].date.toISOString()).toBe("2024-07-29T00:00:00.000Z");
-  });
-});

src/lib/analytics/__tests__/trends.test.ts

@@ -1,6 +1,5 @@
 import { describe, it, expect } from "vitest";
 import {
-  movingAverage,
   trendSlope,
   detectAnomalies,
   summarize,
@@ -15,27 +14,6 @@ function makePoints(values: number[], startDaysAgo = 30): DataPoint[] {
   }));
 }
 
-describe("movingAverage", () => {
-  it("returns empty for empty input", () => {
-    expect(movingAverage([], 7)).toEqual([]);
-  });
-
-  it("calculates moving average over window", () => {
-    const data = makePoints([70, 71, 72, 73, 74, 75, 76], 7);
-    const result = movingAverage(data, 3);
-    expect(result).toHaveLength(7);
-    // Last point should be avg of last 3 days
-    expect(result[result.length - 1].value).toBeCloseTo(75, 0);
-  });
-
-  it("handles single data point", () => {
-    const data = makePoints([100], 1);
-    const result = movingAverage(data, 7);
-    expect(result).toHaveLength(1);
-    expect(result[0].value).toBe(100);
-  });
-});
-
 describe("trendSlope", () => {
   it("returns null for insufficient data", () => {
     expect(trendSlope([], 7)).toBeNull();

src/lib/analytics/correlations.ts

@@ -105,69 +105,3 @@ export function pearsonCorrelation(
   return { r, strength, n };
 }
 
-const BERLIN_DATE_PARTS = new Intl.DateTimeFormat("en-CA", {
-  timeZone: "Europe/Berlin",
-  year: "numeric",
-  month: "2-digit",
-  day: "2-digit",
-  weekday: "short",
-});
-
-/**
- * Aggregate data into weekly averages, ISO-Monday-based, in Europe/Berlin.
- *
- * v3 audit caught a TZ bug here: the previous implementation used
- * `Date.getDay()` / `Date.getDate()` (system local) so on a UTC server, a
- * Sunday-evening Berlin reading bucketed into the next week. We now derive
- * year/month/day/weekday in Berlin via Intl.DateTimeFormat and rebuild the
- * Monday key from there. The returned `date` for each bucket is the Monday
- * UTC midnight — sortable, comparable across DST.
- */
-export function weeklyAverages(data: DataPoint[]): DataPoint[] {
-  if (data.length === 0) return [];
-
-  const sorted = [...data].sort((a, b) => a.date.getTime() - b.date.getTime());
-
-  const weeks = new Map<string, { sum: number; count: number; date: Date }>();
-
-  const WEEKDAY_INDEX: Record<string, number> = {
-    Mon: 1,
-    Tue: 2,
-    Wed: 3,
-    Thu: 4,
-    Fri: 5,
-    Sat: 6,
-    Sun: 7,
-  };
-
-  for (const point of sorted) {
-    const parts = BERLIN_DATE_PARTS.formatToParts(point.date);
-    const yearStr = parts.find((p) => p.type === "year")?.value ?? "1970";
-    const monthStr = parts.find((p) => p.type === "month")?.value ?? "01";
-    const dayStr = parts.find((p) => p.type === "day")?.value ?? "01";
-    const weekdayStr = parts.find((p) => p.type === "weekday")?.value ?? "Mon";
-
-    const isoWeekday = WEEKDAY_INDEX[weekdayStr] ?? 1;
-    // Days to subtract to land on Monday of the same ISO week in Berlin.
-    const offsetDays = isoWeekday - 1;
-
-    const dayUtc = new Date(`${yearStr}-${monthStr}-${dayStr}T00:00:00.000Z`);
-    const monday = new Date(dayUtc.getTime() - offsetDays * 86_400_000);
-    const key = monday.toISOString().slice(0, 10);
-
-    const existing = weeks.get(key);
-    if (existing) {
-      existing.sum += point.value;
-      existing.count++;
-    } else {
-      weeks.set(key, { sum: point.value, count: 1, date: monday });
-    }
-  }
-
-  return Array.from(weeks.values())
-    .sort((a, b) => a.date.getTime() - b.date.getTime())
-    .map((w) => ({
-      date: w.date,
-      value: Math.round((w.sum / w.count) * 100) / 100,
-    }));
-}

src/lib/analytics/trends.ts

@@ -8,33 +8,6 @@ export interface DataPoint {
   value: number;
 }
 
-// ── Moving Average ───────────────────────────────────────
-
-export function movingAverage(
-  data: DataPoint[],
-  windowDays: number,
-): DataPoint[] {
-  if (data.length === 0) return [];
-
-  const sorted = [...data].sort((a, b) => a.date.getTime() - b.date.getTime());
-  const result: DataPoint[] = [];
-  const windowMs = windowDays * 24 * 60 * 60 * 1000;
-
-  for (const point of sorted) {
-    const windowStart = point.date.getTime() - windowMs;
-    const windowPoints = sorted.filter(
-      (p) =>
-        p.date.getTime() > windowStart &&
-        p.date.getTime() <= point.date.getTime(),
-    );
-    const avg =
-      windowPoints.reduce((sum, p) => sum + p.value, 0) / windowPoints.length;
-    result.push({ date: point.date, value: Math.round(avg * 100) / 100 });
-  }
-
-  return result;
-}
-
 // ── Trend Slope ──────────────────────────────────────────
 
 export interface TrendSlope {