secrets tab, drop commute filter, favicon, robust error reports

1. Admin → Geheimnisse sub-tab lets you edit ANTHROPIC_API_KEY +
   BERLIN_WOHNEN_USERNAME/PASSWORD at runtime. Migration v7 adds a
   secrets(key,value,updated_at) table; startup seeds missing keys from
   env (idempotent). web reads secrets DB-first (env fallback) via
   llm._api_key(); alert fetches them from web /internal/secrets on each
   scan, passes them into Scraper(). Rotating creds no longer needs a
   redeploy.
   Masked display: 6 leading + 4 trailing chars, "…" in the middle.
   Blank form fields leave the stored value untouched.

2. Drop the max_morning_commute filter from UI + server + FILTER_KEYS +
   filter summary (the underlying Maps.calculate_score code stays for
   potential future re-enable).

3. /static/didi.webp wired as favicon via <link rel="icon"> in base.html.

4. apply.open_page wraps page.goto in try/except so a failed load still
   produces a "goto.failed" step + screenshot instead of returning an
   empty forensics blob. networkidle + post-submission sleep are also
   made best-effort. The error ZIP export already writes screenshot+HTML
   per step and final_html — with this change every apply run leaves a
   reconstructable trail even when the listing is already offline.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/templates/admin.html

@@ -6,7 +6,7 @@
 {% block content %}
 <section class="card">
     <nav class="flex flex-wrap border-b border-soft px-4">
-        {% set sections = [('protokoll','Protokoll'), ('benutzer','Benutzer')] %}
+        {% set sections = [('protokoll','Protokoll'), ('benutzer','Benutzer'), ('geheimnisse','Geheimnisse')] %}
         {% for key, label in sections %}
         <a href="/admin/{{ key }}"
            class="tab {% if section == key %}active{% endif %}">{{ label }}</a>
@@ -16,6 +16,7 @@
     <div class="p-5">
         {% if section == 'protokoll' %}{% include "_admin_logs.html" %}
         {% elif section == 'benutzer' %}{% include "_settings_users.html" %}
+        {% elif section == 'geheimnisse' %}{% include "_admin_secrets.html" %}
         {% endif %}
     </div>
 </section>