feat(integrations): add create integration review request API and UI

Add a new Tauri command and front-end flow to create PRs/MRs.
The backend builds and validates provider-specific payloads and
endpoints, sends creation requests, and parses responses into the
app's review model. A Svelte dialog and a JS wrapper wire the UI to the
command so users can create requests from the Review Center.

- Implement provider payload and endpoint logic with unit tests
- Expose create_integration_review_request as a Tauri command
- Add CreateReviewDialog UI and integrate a creation button in Review Center

src/lib/components/ReviewCenter.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
   import { onMount } from "svelte";
+  import CreateReviewDialog from "./CreateReviewDialog.svelte";
   import SelectMenu from "./SelectMenu.svelte";
   import { cubicOut } from "svelte/easing";
   import { fly } from "svelte/transition";
@@ -32,6 +33,7 @@
   }
 
   let { language = "en", integrations, initialQuery = "", initialSourceId = "", localResolutionRequestId = "", localResolutionPhase = "idle", localResolutionMessage = "", loadCredential, onOpenSettings = () => {}, onStartLocalResolution = () => {}, onOpenLocalResolver = () => {}, onContinueLocalResolution = () => {}, onAbortLocalResolution = () => {}, onPushLocalResolution = () => {} }: Props = $props();
+  let createOpen = $state(false);
   let requests = $state<IntegrationReviewRequest[]>([]);
   let loading = $state(false);
   let errors = $state<Array<{ source: string; message: string }>>([]);
@@ -398,9 +400,24 @@
   }
 </script>
 
+{#if createOpen && activeSource}
+  <CreateReviewDialog source={activeSource} {de} {loadCredential} onClose={() => createOpen = false} onCreated={(request) => {
+    ++loadGeneration;
+    loading = false;
+    requests = [request, ...requests.filter(item => item.id !== request.id)];
+    stateFilter = request.state;
+    query = "";
+    collapsedRepositories = new Set();
+    errors = [];
+    createOpen = false;
+    selectRequest(request, true);
+  }}/>
+{/if}
+
 <section class:has-inspector={detailOpen && !!selected} class="review-center" aria-label="Review Center">
   <header class="review-header">
     <div class="review-heading"><GitPullRequest size={17} /><h1>Review Center</h1></div>
+    {#if activeSource}<button class="create-review" type="button" disabled={loading} onclick={() => { detailOpen = false; createOpen = true; }}><GitPullRequest size={14}/>{activeSource.provider.startsWith("gitlab") ? (de ? "MR erstellen" : "Create MR") : (de ? "PR erstellen" : "Create PR")}</button>{/if}
   </header>
 
   {#if sources.length === 0}
@@ -528,6 +545,7 @@
 </section>
 
 <style>
+  .create-review{margin-left:auto;display:flex;align-items:center;gap:7px;padding:7px 11px;border:1px solid var(--color-border-subtle);border-radius:7px;background:var(--color-accent);color:white;cursor:pointer}.create-review:disabled{opacity:.5;cursor:default}
   .review-center{display:flex;min-height:0;flex:1;flex-direction:column;overflow:hidden;color:var(--color-ink);background:var(--app-bg);font-size:12px}.review-center button,.review-center input{font:inherit}.review-header{display:flex;min-height:48px;align-items:center;padding:0 18px;border-bottom:1px solid var(--color-border-subtle);background:var(--color-surface)}.review-heading{display:flex;align-items:center;gap:9px}.review-heading>:global(svg){color:var(--color-accent)}.review-heading h1{margin:0;font-size:16px;font-weight:650}
   .state-tabs{display:flex;min-height:42px;align-items:stretch;gap:18px;padding:0 18px;border-bottom:1px solid var(--color-border-subtle);background:var(--color-surface)}.state-tabs button{position:relative;display:flex;align-items:center;gap:7px;padding:0 5px;border:0;color:var(--color-ink-muted);background:transparent;font-size:11px}.state-tabs button:hover{color:var(--color-ink)}.state-tabs button.active{color:var(--color-accent)}.state-tabs button.active:after{position:absolute;right:0;bottom:0;left:0;height:2px;background:var(--color-accent);content:""}.state-tabs span,.group-header>span{display:grid;min-width:18px;height:18px;place-items:center;padding:0 5px;border-radius:9px;color:var(--color-ink-muted);background:var(--color-surface-raised);font-size:9.5px}
   .review-toolbar{display:flex;min-height:48px;align-items:center;gap:10px;padding:7px 18px;border-bottom:1px solid var(--color-border-subtle)}.group-actions{display:flex;align-items:center;gap:2px}.group-actions button,.icon-button{display:inline-flex;height:30px;align-items:center;gap:5px;padding:0 7px;border:1px solid transparent;color:var(--color-ink-muted);background:transparent}.group-actions button:hover,.icon-button:hover{border-color:var(--color-border);color:var(--color-ink);background:var(--color-surface-hover)}.group-actions .icon-button{width:30px;justify-content:center;padding:0;border-color:var(--color-border-subtle);margin-left:3px}.review-search{display:flex;min-width:180px;height:30px;align-items:center;gap:7px;flex:1;padding:0 9px;border:1px solid var(--color-border-input);color:var(--color-ink-faint);background:var(--app-input-bg)}.review-search:focus-within{border-color:var(--color-accent)}.review-search input{width:100%;min-width:0;height:100%;padding:0;border:0;outline:0;color:var(--color-ink);background:transparent}