Improve asr heuristics

[ShaohongZ]

Overview

Included heuristics information to improve ASR detection results

Type of change

• Bug fix
• [v ] New feature
• Documentation improvement
• Bounty issue submission
• Other:

Changes

• Directed-at-robot filter: Added _seems_directed_at_robot() heuristic that checks for keywords (greetings, question words, robot names, conference terms) and question marks. Filters out overheard chatter not intended for the robot.
• ASR text normalization: Added _normalize_asr_text() with _ASR_CORRECTIONS to fix common misrecognitions (e.g. "om one" → "OM1", "open mind" → "OpenMind", "unit tree" → "Unitree").
• Minimum word count filter: Messages with 2 or fewer words are ignored to reduce noise from short non-speech sounds.
• Applied to both riva_asr.py (microphone input) and riva_asr_rtsp.py (RTSP stream input). The RTSP variant imports shared filter functions from riva_asr.py to avoid duplication.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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