[AI] Route AI calls through the Xray/V2Ray proxy (reach OpenAI from Iran)

Add AiUseProxy setting + a toggle in the AI settings section. ScrapeHttpClients.ForAi(settings) returns a proxied HttpClient (reusing IngestProxyUrl, 100s timeout) when AiUseProxy is on, otherwise direct; AI-cache keys are protected from the scrape-client cleanup. OpenAiCompatibleAuditor now uses it, so the AI auditor (e.g. api.openai.com) is reachable through the same Xray sidecar that serves Telegram. Migration adds the column.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/JobsMedical.Web/Migrations/20260607192007_AiUseProxy.cs

@@ -0,0 +1,29 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace JobsMedical.Web.Migrations
+{
+    /// <inheritdoc />
+    public partial class AiUseProxy : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<bool>(
+                name: "AiUseProxy",
+                table: "AppSettings",
+                type: "boolean",
+                nullable: false,
+                defaultValue: false);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "AiUseProxy",
+                table: "AppSettings");
+        }
+    }
+}

src/JobsMedical.Web/Migrations/AppDbContextModelSnapshot.cs

@@ -53,6 +53,9 @@ namespace JobsMedical.Web.Migrations
                         .HasMaxLength(4000)
                         .HasColumnType("character varying(4000)");
 
+                    b.Property<bool>("AiUseProxy")
+                        .HasColumnType("boolean");
+
                     b.Property<bool>("AutoIngestEnabled")
                         .HasColumnType("boolean");