fix(providers): rename Freepik slug to Magnific and validate Magnific API keys (#10594)

Canonical provider id renamed freepik → magnific (Magnific Mystic official API), with a permanent redirect + runtime alias so old freepik/<model> traffic and /dashboard/providers/freepik URLs keep working. Existing provider=freepik connection rows are rewritten to magnific by migration 160.

Closes #10604.

Validated in an isolated worktree boarded onto origin/release/v3.8.50 (0 conflicts, 138 files):
- Focused suite: 54/54 tests pass (magnific-image-handler, provider-validation-image-only, provider-alias-uniqueness, redirects-cli-renames).
- check-file-size, check-changelog-integrity: OK.
- typecheck:core: clean.
- check-complexity / check-cognitive-complexity: OK, both under baseline.

Co-authored-by: RaviTharuma <RaviTharuma@users.noreply.github.com>

src/app/api/providers/route.ts

@@ -17,6 +17,7 @@ import {
   isClaudeCodeCompatibleProvider,
   isOpenAICompatibleProvider,
   isAnthropicCompatibleProvider,
+  resolveProviderId,
 } from "@/shared/constants/providers";
 import { getConsistentMachineId } from "@/shared/utils/machineId";
 import { syncToCloud } from "@/lib/cloudSync";
@@ -114,7 +115,7 @@ export async function POST(request: Request) {
       return NextResponse.json({ error: validation.error }, { status: 400 });
     }
     const {
-      provider,
+      provider: requestedProvider,
       apiKey,
       name,
       priority,
@@ -123,6 +124,7 @@ export async function POST(request: Request) {
       testStatus,
       providerSpecificData: incomingPsd,
     } = validation.data;
+    const provider = resolveProviderId(requestedProvider);
 
     // Business validation
     const isValidProvider =

src/app/api/v1/models/catalog.ts

@@ -519,13 +519,11 @@ async function buildUnifiedModelsResponseCore(
       const targetModel = getComboTargetModelId(target);
       if (!targetModel) return null;
 
-      const canonical = getCanonicalModelMetadata(
-        {
-          provider: targetModel.providerId,
-          model: targetModel.modelId,
-        },
-        capabilityResolutionSnapshot
-      );
+      const canonical = getCanonicalModelMetadata({
+        provider: targetModel.providerId,
+        model: targetModel.modelId,
+        snapshot: capabilityResolutionSnapshot,
+      });
       if (!canonical) return null;
 
       const providerId = canonical.provider || targetModel.providerId;

src/app/api/v1/responses/route.ts

@@ -1,3 +1,4 @@
+import { z } from "zod";
 import { handleChat } from "@/sse/handlers/chat";
 import { CORS_HEADERS } from "@/shared/utils/cors";
 import { createInjectionGuard } from "@/middleware/promptInjectionGuard";
@@ -114,9 +115,11 @@ async function postHandler(request: any) {
     } catch {
       return finishAdmission(errorResponse(400, "Invalid JSON body"));
     }
-    if (!parsedBody || typeof parsedBody !== "object" || Array.isArray(parsedBody)) {
+    const parsed = z.object({}).passthrough().safeParse(parsedBody);
+    if (!parsed.success || Array.isArray(parsed.data)) {
       return finishAdmission(errorResponse(400, "Request body must be a JSON object"));
     }
+    parsedBody = parsed.data;
 
     const structuralAdmission = await admitChatStructure(parsedBody, admission.lease, {
       sessionId,