fix(db): drop deprecated contact.application_id from schema

The contact_application junction commit (1d0235a) had already dropped the
deprecated applicationId column from the live DB via migration 0001, but
schema.ts was left with the column declaration (it was put back temporarily
during commit preparation to keep schema.ts consistent with 0000_init.sql,
then never re-removed for the junction commit). This caused Drizzle to
generate INSERTs against a non-existent column when creating contacts.

Schema.ts now matches the live DB; no migration needed (0001 already
dropped the column).

src/db/schema.ts

@@ -247,11 +247,6 @@ export const contact = pgTable(
     companyId: integer("company_id").references(() => company.id, {
       onDelete: "set null",
     }),
-    // Deprecated: use contactApplication junction for many-to-many. Kept for
-    // backward compatibility with existing queries; remove after migrating callers.
-    applicationId: integer("application_id").references(() => application.id, {
-      onDelete: "set null",
-    }),
     name: text("name").notNull(),
     role: text("role"),
     email: text("email"),
@@ -261,10 +256,7 @@ export const contact = pgTable(
     lastContactDate: text("last_contact_date"),
     ...timestamps,
   },
-  (table) => [
-    index("idx_contact_company").on(table.companyId),
-    index("idx_contact_application").on(table.applicationId),
-  ]
+  (table) => [index("idx_contact_company").on(table.companyId)]
 );
 
 export const promptConfig = pgTable("prompt_config", {