feat(manual-entry): bulk and single entry for the feeds no API serves

Egg, milk and fodder have no usable API for the pilot districts — NECC
publishes HTML, dairy rates exist only as annual state averages, and every
recent Agmarknet fodder row is one market in Ambala. This is how a bank
gets that data in.

Upload stages a PREVIEW batch and writes nothing. It reports what would
land, what was rejected and why, and which rows would overwrite an
existing value. Only commit touches market_signal.

Effective dating: effective_date is the date the fact describes and comes
from the file; observedAt is when we learned it and is stamped at commit.
The uploader cannot reach observedAt — a March rate uploaded in August
must stay invisible to a March scoring run, or the model trains on data
that did not exist yet.

Rejections name themselves: UNKNOWN_DISTRICT, UNKNOWN_COMMODITY,
FUTURE_DATE, BAD_DATE, BAD_NUMBER, UNIT_MISMATCH, PRICE_ORDER,
DUPLICATE_IN_FILE, MISSING_REQUIRED. A price far from last week warns but
is accepted — a genuine price shock is the event this system exists to
catch, and rejecting it would be backwards.

Rows are written with source=MANUAL, which the unique index keeps separate
from a feed's own row for the same week, so manual data never silently
replaces a government feed.

Also distinguishes INSUFFICIENT_HISTORY from NO_SIGNAL in the price
derivations. A newly onboarded manual feed spends its first weeks below
the four-week minimum, and reporting NO_SIGNAL there reads as a broken
integration rather than a series still filling up.

Result: margin_squeeze and output_price_change compute for the first time
— 57 of 142 enterprises, exactly the DAIRY (30) and POULTRY (27) sectors
that have an output commodity.

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

src/main/java/com/lincfusion/udyamlinc/manualentry/ManualEntryBatch.java

@@ -0,0 +1,72 @@
+package com.lincfusion.udyamlinc.manualentry;
+
+import jakarta.persistence.*;
+import lombok.*;
+
+import java.time.LocalDateTime;
+
+/**
+ * One upload. The audit anchor for every manually-sourced number in the system:
+ * a supervisor asking "where did Bhopal's March milk rate come from" gets a
+ * filename, a person and a timestamp, not a shrug.
+ *
+ * <p>A batch is staged as {@code PREVIEW} and writes nothing. Only
+ * {@code COMMITTED} has touched {@code market_signal}. Uploading four hundred
+ * rows and discovering the district column was misspelled afterwards is not a
+ * recoverable situation, so nothing lands until someone has seen what will.
+ */
+@Entity
+@Table(name = "manual_entry_batch", indexes = {
+        @Index(name = "ix_manual_batch_status", columnList = "status"),
+        @Index(name = "ix_manual_batch_uploaded", columnList = "uploadedAt"),
+})
+@Getter
+@Setter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class ManualEntryBatch {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    /** MARKET_SIGNAL | LOAN_RECORD — which template was uploaded. */
+    @Column(nullable = false, length = 32)
+    private String entryType;
+
+    @Column(length = 260)
+    private String filename;
+
+    /** The username from the JWT. Never a display name — this is an audit field. */
+    @Column(nullable = false, length = 64)
+    private String uploadedBy;
+
+    @Column(nullable = false)
+    private LocalDateTime uploadedAt;
+
+    /** PREVIEW | COMMITTED | DISCARDED. */
+    @Column(nullable = false, length = 16)
+    private String status;
+
+    private LocalDateTime committedAt;
+
+    @Column(length = 64)
+    private String committedBy;
+
+    private Integer rowsParsed;
+    private Integer rowsAccepted;
+    private Integer rowsRejected;
+
+    /** How many accepted rows would replace a value that already exists. */
+    private Integer rowsOverwriting;
+
+    @Column(length = 500)
+    private String note;
+
+    @PrePersist
+    void onCreate() {
+        if (uploadedAt == null) uploadedAt = LocalDateTime.now();
+        if (status == null) status = "PREVIEW";
+    }
+}