docs: add theme showcase gif to README

Raise pre-commit large file limit from 500 KB to 1 MB to accommodate
documentation assets.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 0xzerolight

.pre-commit-config.yaml

@@ -6,7 +6,7 @@ repos:
       - id: end-of-file-fixer
       - id: check-yaml
       - id: check-added-large-files
-        args: ['--maxkb=500']
+        args: ['--maxkb=1024']
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
     rev: v0.15.5

README.md

@@ -7,6 +7,10 @@
 
 Self-hosted news monitoring with LLM-powered novelty detection. Watches topics via RSS feeds, notifies you only when genuinely new information appears. BYOK (bring your own key).
 
+<p align="center">
+  <img src="docs/themes-showcase.gif" alt="Topic Watch — theme showcase" width="720">
+</p>
+
 ## How It Works
 
 1. Define topics with RSS feed URLs, or let it auto-generate a Google News feed