wiki: add alternatives section with SearXNG, FreshRSS, and Gitea

Add three new articles to 03-opensource/alternatives/:
- SearXNG: private metasearch, Open WebUI integration
- FreshRSS: self-hosted RSS, mobile app sync, OPML portability
- Gitea: lightweight GitHub alternative, webhook pipeline

Article count: 33 → 36. Open source section: 6 → 9.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

03-opensource/alternatives/searxng.md

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+# SearXNG — Private Self-Hosted Search
+
+## Problem
+
+Every search query sent to Google, Bing, or DuckDuckGo is logged, profiled, and used to build an advertising model of you. Even "private" search engines are still third-party services with their own data retention policies.
+
+## Solution
+
+[SearXNG](https://github.com/searxng/searxng) is a self-hosted metasearch engine. It queries multiple search engines simultaneously on your behalf — without sending any identifying information — and aggregates the results. The search engines see a request from your server, not from you.
+
+Your queries stay on your infrastructure.
+
+---
+
+## Deployment (Docker)
+
+```yaml
+services:
+  searxng:
+    image: searxng/searxng:latest
+    container_name: searxng
+    restart: unless-stopped
+    ports:
+      - "8090:8080"
+    volumes:
+      - ./searxng:/etc/searxng
+    environment:
+      - SEARXNG_BASE_URL=https://search.yourdomain.com/
+```
+
+SearXNG requires a `settings.yml` in the mounted config directory. Generate one from the default:
+
+```bash
+docker run --rm searxng/searxng cat /etc/searxng/settings.yml > ./searxng/settings.yml
+```
+
+Key settings to configure in `settings.yml`:
+
+```yaml
+server:
+  secret_key: "generate-a-random-string-here"
+  bind_address: "0.0.0.0"
+
+search:
+  safe_search: 0
+  default_lang: "en"
+
+engines:
+  # Enable/disable specific engines here
+```
+
+### Caddy reverse proxy
+
+```
+search.yourdomain.com {
+    reverse_proxy localhost:8090
+}
+```
+
+---
+
+## Using SearXNG as an AI Search Backend
+
+SearXNG integrates directly with Open WebUI as a web search provider, giving your local AI access to current web results without any third-party API keys:
+
+**Open WebUI → Settings → Web Search:**
+- Enable web search
+- Set provider to `searxng`
+- Set URL to `http://searxng:8080` (internal Docker network) or your Tailscale/local address
+
+This is how MajorTwin gets current web context — queries go through SearXNG, not Google.
+
+---
+
+## Why Not DuckDuckGo?
+
+DDG is better than Google for privacy, but it's still a centralized third-party service. SearXNG:
+
+- Runs on your own hardware
+- Has no account, no cookies, no session tracking
+- Lets you choose which upstream engines to use and weight
+- Can be kept entirely off the public internet (Tailscale-only)
+
+---
+
+## Tags
+
+#searxng #search #privacy #self-hosting #docker #linux #alternatives