chore(skills): Add RSS feed for Svelte blog to sources

[s1gr1d]

Adds the SvelteKit blog: https://svelte.dev/blog

[sentry]

Bug: The same RSS feed URL is configured for both the Svelte and SvelteKit frameworks in sources.json, leading to duplicate data processing and reporting.
_{Severity: MEDIUM}

Suggested Fix

To prevent duplicate entries, the SvelteKit entry in sources.json should be updated to point to a SvelteKit-specific RSS feed if one exists. If a separate feed is not available, the RSS entry for SvelteKit should be removed to avoid duplication, as the Svelte entry already tracks this shared blog.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: .agents/skills/track-framework-updates/sources.json#L156

Potential issue: The configuration in `sources.json` assigns the same RSS feed URL,
`"https://svelte.dev/blog/rss.xml"`, to both the "Svelte" and "SvelteKit" frameworks.
The processing scripts, `fetch_rss.py` and `collect_updates.py`, iterate through
frameworks independently and lack cross-framework deduplication logic. As a result,
articles from this feed will be fetched twice and will appear under both frameworks in
the final output. This will cause the agent to report the same articles twice in its
digest, creating redundancy and making the report misleading.

Also affects:

• .agents/skills/track-framework-updates/sources.json:46

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[s1gr1d]

Closing this because I think tracking the blog URL via "Svelte" should be enough.