chore: remove news feed feature (#17)

## Summary

- Removes the hourly RSS news posting scheduler and `postNews` module
- Removes the `rss.ts` interface and `lastRssItems` tracking from the `Amari` interface and bot initialisation
- Removes the `news` channel ID from `ids.ts`
- Removes the `rss-parser` dependency

✨ This PR was created with help from Hikari~ 🌸

Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Reviewed-on: #17
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

package.json

@@ -30,7 +30,6 @@
     "discord.js": "14.22.0",
     "fastify": "5.7.4",
     "node-schedule": "2.1.1",
-    "octokit": "5.0.5",
-    "rss-parser": "3.13.0"
+    "octokit": "5.0.5"
   }
 }