Fix database schema: Change auction_id and lot_id from BIGINT to TEXT

The scraper uses TEXT IDs like "A7-40063-2" but DatabaseService was creating
BIGINT columns, causing PRIMARY KEY constraint failures on the server.

Changes:
- auction_id: BIGINT -> TEXT PRIMARY KEY
- lot_id: BIGINT -> TEXT PRIMARY KEY
- sale_id: BIGINT -> TEXT
- Added UNIQUE constraints on URLs
- Added migration script (fix-schema.sql)

This fixes the "UNIQUE constraint failed: auctions.auction_id" errors
and allows bid data to populate correctly on the server.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Former-commit-id: 12c3a732e4

src/main/java/auctiora/DatabaseService.java

@@ -40,14 +40,15 @@ public class DatabaseService {
          stmt.execute("PRAGMA synchronous=NORMAL");
 
          // Auctions table (populated by external scraper)
+         // auction_id is TEXT to match scraper format (e.g., "A7-40063-2")
          stmt.execute("""
                               CREATE TABLE IF NOT EXISTS auctions (
-                                  auction_id BIGINT PRIMARY KEY,
+                                  auction_id TEXT PRIMARY KEY,
                                   title TEXT NOT NULL,
                                   location TEXT,
                                   city TEXT,
                                   country TEXT,
-                                  url TEXT NOT NULL,
+                                  url TEXT NOT NULL UNIQUE,
                                   type TEXT,
                                   lot_count INTEGER DEFAULT 0,
                                   closing_time TEXT,
@@ -55,10 +56,12 @@ public class DatabaseService {
                               )""");
 
          // Lots table (populated by external scraper)
+         // lot_id and sale_id are TEXT to match scraper format (e.g., "A1-34732-49")
          stmt.execute("""
                               CREATE TABLE IF NOT EXISTS lots (
-                                  lot_id BIGINT PRIMARY KEY,
-                                  sale_id BIGINT,
+                                  lot_id TEXT PRIMARY KEY,
+                                  sale_id TEXT,
+                                  auction_id TEXT,
                                   title TEXT,
                                   description TEXT,
                                   manufacturer TEXT,
@@ -67,18 +70,20 @@ public class DatabaseService {
                                   category TEXT,
                                   current_bid REAL,
                                   currency TEXT,
-                                  url TEXT,
+                                  url TEXT UNIQUE,
                                   closing_time TEXT,
                                   closing_notified INTEGER DEFAULT 0,
-                                  FOREIGN KEY (sale_id) REFERENCES auctions(auction_id)
+                                  FOREIGN KEY (sale_id) REFERENCES auctions(auction_id),
+                                  FOREIGN KEY (auction_id) REFERENCES auctions(auction_id)
                               )""");
 
          // Images table (populated by external scraper with URLs and local_path)
          // This process only adds labels via object detection
+         // lot_id is TEXT to match scraper format
          stmt.execute("""
                               CREATE TABLE IF NOT EXISTS images (
                                   id INTEGER PRIMARY KEY AUTOINCREMENT,
-                                  lot_id INTEGER,
+                                  lot_id TEXT,
                                   url TEXT,
                                   local_path TEXT,
                                   labels TEXT,