Feat/gst consumer capture time

[TangmereCottage]

Consume the synchronized A+V stream + stamp ASR audio at capture

Pairs OM1 with the OM1-video-processor GStreamer pipeline, which serves a single
muxed A+V RTSP session (rtsp://localhost:8555/live) on one clock. Two parts:
config (repoint consumers) and code (stamp audio capture time at ingest).

Config — repoint consumers (non-breaking)

config/unitree_g1_conversation.json5 is env-parametrized; defaults preserve
current behavior exactly:

• ASR: type: "${ASR_INPUT_PLUGIN:-GoogleASRInput}" + rtsp_url: "${ASR_RTSP_URL:-rtsp://localhost:8555/live}" (the local plugin ignores the
  extra key).
• VLM: rtsp_url: "${VLM_RTSP_URL:-rtsp://localhost:8554/top_camera_raw}"
  (unchanged default).

docker-compose.yml exposes ASR_INPUT_PLUGIN, ASR_RTSP_URL, VLM_RTSP_URL.
To consume the GStreamer stream:

ASR_INPUT_PLUGIN=GoogleASRRTSPInput \
ASR_RTSP_URL=rtsp://localhost:8555/live \
VLM_RTSP_URL=rtsp://localhost:8555/live \
docker compose up -d om1

Both consumers read the same muxed URL; each ffmpeg selects its track
(google_asr_rtsp uses -vn, video_rtsp_stream uses -an), so audio and
video come from one synchronized source.

Code — stamp ASR audio at capture

Previously the audio timestamp was set at package/send time
(packageAudio → time.Now().UnixMilli()), discarding capture timing. Now:

• packageAudio(pcm, captureMs) stamps the provided capture time.
• sendChunkAt(pcm, capture) added; sendChunk kept as a time.Now() wrapper
  for back-compat (riva/elevenlabs/parallel unchanged — trivially extendable).
• google_asr.go (local mic) and google_asr_rtsp.go (RTSP) stamp
  time.Now() at the moment the buffer/chunk is read and pass it through.
• Tests updated to pass and assert the capture timestamp.

This makes ASR chunks carry capture time, so downstream alignment with
video-derived features works on a common timeline.

Deliberately out of scope (follow-ups)

• Transcript→capture-time mapping across the cloud round-trip. The final
  transcript still reaches the IO layer without a capture timestamp
  (asr_common.go AddInput(..., time.Time{})); mapping it back to the source
  audio window needs the ASR WS protocol to echo timestamps.
• Video RTSP PTS. JPEG-over-image2pipe carries no per-frame PTS; true
  capture-time for video needs a PTS-preserving transport (documented at the
  stamp site in video_rtsp_stream.go).
• Extend sendChunkAt to the riva/elevenlabs paths (one-line each).

Verification

Config validated as JSON5; compose validated as YAML. The Go changes are
mechanical (caller consistency checked: sendChunk still present; only the two
packageAudio test call sites updated) but were not compiled in this
environment — run go build ./... && go test ./plugins/inputs/asr/... in CI.

[codecov]

Codecov Report

❌ Patch coverage is 65.51724% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
plugins/inputs/asr/elevenlabs_asr.go	0.00%	2 Missing ⚠️
plugins/inputs/asr/google_asr.go	0.00%	2 Missing ⚠️
plugins/inputs/asr/riva_asr.go	0.00%	2 Missing ⚠️
internal/providers/vlm/video_rtsp_stream.go	66.66%	1 Missing ⚠️
plugins/inputs/asr/elevenlabs_asr_rtsp.go	50.00%	1 Missing ⚠️
plugins/inputs/asr/google_asr_rtsp.go	50.00%	1 Missing ⚠️
plugins/inputs/asr/riva_asr_rtsp.go	50.00%	1 Missing ⚠️

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