Slice 12: inline command-result toasts

New <toast-host> overlay: components post 'toast' CustomEvents ({message, kind: success|error|info}) and it shows brief, auto-dismissing, bottom-right toasts (errors linger). <repo-menu> (git + coordination actions) and <pr-list> (create/merge) now post friendly success/error toasts instead of alert(); the activity feed still logs everything. Also adds the slice 11 CHANGELOG entry. Verified live: 'Checked for updates' toast shown.

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

components/pr-list/pr-list.js

@@ -59,12 +59,17 @@ class PRList extends HTMLElement {
       });
       const data = await res.json();
       if (!res.ok) throw new Error(data.error || `HTTP ${res.status}`);
+      this.#toast(`Merged & cleaned up PR #${pr.number}`, 'success');
       this.#load(this.#path); // refresh the list
     } catch (err) {
-      this.#error(`Merge failed: ${err.message}`);
+      this.#toast(`Merge failed: ${err.message}`, 'error');
     }
   }
 
+  #toast(message, kind) {
+    document.dispatchEvent(new CustomEvent('toast', { detail: { message, kind } }));
+  }
+
   async #create() {
     const branch = this.#repo?.branch;
     if (!branch) return;
@@ -78,9 +83,10 @@ class PRList extends HTMLElement {
       });
       const data = await res.json();
       if (!res.ok) throw new Error(data.error || `HTTP ${res.status}`);
+      this.#toast(`Opened PR #${data.number}`, 'success');
       this.#load(this.#path); // refresh so the new PR appears
     } catch (err) {
-      window.alert(`Create PR failed: ${err.message}`);
+      this.#toast(`Create PR failed: ${err.message}`, 'error');
     }
   }