Remove UseHeadlessBrowser from JobProvider — all fetches now go via page-fetcher-api

page-fetcher-api always uses Playwright (networkidle by default), so the
per-provider flag that chose between headless and plain HTTP is obsolete.

- Removed from JobProviderEntity, CvSearchDbContext, JobProviderConfig, JobTokenService
- HtmlJobSearcher no longer passes WaitFor (uses page-fetcher-api default)
- EF migration drops the column from cvSearch.JobProviders

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Apis/cv-search-data/Migrations/20260608154221_RemoveUseHeadlessBrowser.cs

@@ -0,0 +1,32 @@
+using CvSearch.Data;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace CvSearch.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class RemoveUseHeadlessBrowser : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "UseHeadlessBrowser",
+                schema: MigrationConstants.SchemaName,
+                table: "JobProviders");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<bool>(
+                name: "UseHeadlessBrowser",
+                schema: MigrationConstants.SchemaName,
+                table: "JobProviders",
+                type: "bit",
+                nullable: false,
+                defaultValue: false);
+        }
+    }
+}