Replace Clay with n8n, Ollama, SearXNG and browserless; add Telegram assistant

Remove the Clay role (Claude Code web UI) and its Anthropic API key.

New roles:
- ollama: local CPU LLM (qwen3:4b-instruct), internal network only
- browserless: headless Chromium for JavaScript-heavy pages
- searxng: metasearch backend for the chat web_search tool
- n8n at agent.ladkau.de: web chat (/chat), scheduled workflows,
  Telegram bot; workflows and credentials are imported from the repo

Telegram bot: Gemini 3.8 -> Gemini 3.5 -> local Qwen fallback chain,
/qwen to force the local model, /stocks and a weekday schedule
(07:30, 13:00, 17:40) for the MTE.DE / PTX.F stock report.

Also: dashboard and check-services entries for the chat, vault checks
for the new secrets (n8n, SearXNG, Gemini, Telegram, SMTP), updated
CLAUDE.md, runbooks and README.

ansible/roles/searxng/templates/settings.yml.j2

@@ -0,0 +1,24 @@
+# Managed by Ansible — do not edit manually
+use_default_settings: true
+
+general:
+  instance_name: "search"
+  enable_metrics: false
+
+server:
+  secret_key: "{{ searxng_secret_key }}"
+  # Internal use only (no public route), so the bot limiter is not needed
+  limiter: false
+  image_proxy: false
+
+search:
+  # json is required by the n8n web_search tool
+  formats:
+    - html
+    - json
+  safe_search: 0
+  autocomplete: ""
+
+outgoing:
+  request_timeout: 6.0
+  max_request_timeout: 10.0