Add pdf-invoice module: one invoice in OpenPDF 3.0.5, iText Core 9.8.0 and Flying Saucer 10.7.0, Devanagari shaping checked by rendering, streamed vs buffered download, subset sizes and timings

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b6Kg9RWSTJzyz6KP9X

pdf-invoice/src/main/java/com/ankurm/pdfinvoice/Money.java

@@ -0,0 +1,29 @@
+package com.ankurm.pdfinvoice;
+
+import java.math.BigDecimal;
+import java.text.NumberFormat;
+import java.util.Locale;
+
+/**
+ * Rupee formatting with Indian digit grouping (12,34,567.00), shared by all three writers.
+ * It is a class of our own because Thymeleaf 3.1 refuses to call methods on {@code java.*} types
+ * from a template expression ("Calling method 'format' is forbidden for type DecimalFormat").
+ */
+public final class Money {
+
+    private Money() {}
+
+    public static String inr(BigDecimal v) {
+        NumberFormat f = NumberFormat.getNumberInstance(Locale.of("en", "IN"));
+        f.setMinimumFractionDigits(2);
+        f.setMaximumFractionDigits(2);
+        return "₹ " + f.format(v);
+    }
+
+    /** Template-friendly instance wrapper: {@code ${money.inr(x)}}. */
+    public static final class Fmt {
+        public String inr(BigDecimal v) {
+            return Money.inr(v);
+        }
+    }
+}