chore: initial commit — UdyamLinc backend, phases A-E

Spring Boot 4 / Java 17 / Postgres. Masters and serving (A), Agmarknet and
climate ingestion (B), feature store with 14 derivations (C), SpEL rule
engine and risk scoring (D).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/main/java/com/lincfusion/udyamlinc/ingestion/Weeks.java

@@ -0,0 +1,30 @@
+package com.lincfusion.udyamlinc.ingestion;
+
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.temporal.WeekFields;
+
+/**
+ * Everything upstream reports daily; everything downstream reads weekly. One
+ * definition of "week" for both signal tables, so a mandi price and a rainfall
+ * figure for the same period actually line up.
+ */
+public final class Weeks {
+
+    private Weeks() {}
+
+    /** Monday of the ISO week the date falls in. */
+    public static LocalDate startOf(LocalDate date) {
+        return date.with(DayOfWeek.MONDAY);
+    }
+
+    /** ISO week number, 1–53. */
+    public static int isoWeek(LocalDate date) {
+        return date.get(WeekFields.ISO.weekOfWeekBasedYear());
+    }
+
+    /** ISO week-based year — not always the calendar year at a year boundary. */
+    public static int isoYear(LocalDate date) {
+        return date.get(WeekFields.ISO.weekBasedYear());
+    }
+}