refactor: rename Fabled Assistant to Fabled Scribe

Updates user-visible branding across frontend (PWA manifest, page title,
Settings, push fallback), backend (email templates and subjects, LLM
system prompt, CalDAV displayname, SMTP from-name default), README,
quickstart compose, and MCP server description.

Also updates the CI image path and quickstart image reference to
git.fabledsword.com/bvandeusen/fabledscribe in preparation for the
Forgejo repo rename. Internal Python package, env vars, and database
schema unchanged.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/views/SettingsView.vue

@@ -501,7 +501,7 @@ const smtp = ref({
   smtp_username: "",
   smtp_password: "",
   smtp_from_address: "",
-  smtp_from_name: "Fabled Assistant",
+  smtp_from_name: "Fabled Scribe",
   smtp_use_tls: "true",
 });
 const savingSmtp = ref(false);
@@ -1981,7 +1981,7 @@ function formatUserDate(iso: string): string {
 
       <section class="settings-section full-width">
         <h2>About</h2>
-        <p class="version-line">Fabled Assistant <span class="version-badge">{{ appVersion }}</span></p>
+        <p class="version-line">Fabled Scribe <span class="version-badge">{{ appVersion }}</span></p>
       </section>
 
     </div>
@@ -2741,7 +2741,7 @@ FABLE_API_KEY={{ effectiveApiKey }}</pre>
           </div>
           <div class="field">
             <label for="smtp-from-name">From Name</label>
-            <input id="smtp-from-name" v-model="smtp.smtp_from_name" type="text" placeholder="Fabled Assistant" class="input" />
+            <input id="smtp-from-name" v-model="smtp.smtp_from_name" type="text" placeholder="Fabled Scribe" class="input" />
           </div>
         </div>
         <div class="checkbox-field">