Remove Multi-Seed Filter feature

- Removed src/multiSeedFilter.js from manifest.json
- Deleted multiSeedFilter.js file
- Feature was not working properly (always returned 0 matches)
- Depends on float data being loaded which has reliability issues
- Simplifies extension codebase

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: rainerstudios

manifest.json

@@ -36,7 +36,7 @@
         "https://steamcommunity.com/id/*/tradehistory",
         "https://steamcommunity.com/profiles/*/tradehistory"
       ],
-      "js": ["lib/marketIntelligence.js", "lib/inventoryEnhancer.js", "src/infiniteScroll.js", "src/buff163Integration.js", "src/multiSeedFilter.js", "src/item3DPreview.js", "content.js"],
+      "js": ["lib/marketIntelligence.js", "lib/inventoryEnhancer.js", "src/infiniteScroll.js", "src/buff163Integration.js", "src/item3DPreview.js", "content.js"],
       "css": ["styles/main.css", "styles/inventory.css"],
       "run_at": "document_idle"
     }