Added 2 keywords and 2 subreddits to the Reddit fetching pipeline.

[agentksimha]

Keywords added:

• "feel like a burden" — one of the most documented cognitive distortions in suicidal ideation literature; not covered by existing keywords
• "nobody cares about me" — captures social isolation, a distinct signal absent from the current list

Subreddits added:

• r/healthanxiety — active community; covers health-related anxiety distinct from the general r/Anxiety already included
• r/KindVoice — users explicitly post when struggling and request support; high signal-to-noise for genuine distress expressions

Why:
Current keyword list focuses on acute crisis language. These additions extend coverage to early-stage distress cognitions (burden, isolation) that precede crisis escalation — improving dataset breadth for downstream sentiment analysis.