Stream devices live, add agent companion mode, finish unified trails

[handstandsam]

Summary

Syncs the latest upstream changes through 2026.07.21, bringing in:

• Live device streaming everywhere: the /devices viewer and the Trail Runner device mirror now stream continuous H.264 video for Android devices, iOS simulators (via baguette serve), web browsers (CDP screencast), and Electron apps — with graceful fallback to screenshot polling when a stream source isn't available, and parameter sets kept on every keyframe so mid-stream joins decode cleanly.
• Companion mode: agent-attached authoring sessions. A coding agent owns a trail folder's files while Trail Runner opens a read-only live view the human can watch and steer via standing directives, guided recording, and review requests (trailblaze companion start/listen/respond, --agent-help for the contract).
• Unified trail format completion: every remaining v1 blaze.yaml / per-device *.trail.yaml under trails/ is converted to the single unified trail.yaml shape, and the v1 trail migrator plus its migrate-trails command are removed. Unified trails delegated to the daemon now run on the driver they pin.
• Persistent binary Android transport: host↔device RPC and log delivery move to multiplexed Wire-protobuf WebSockets (new trailblaze-ondevice-rpc-proto module), with HTTP/JSON fallback and a TRAILBLAZE_ANDROID_WIRE_TRANSPORT rollback switch.
• Video in reports: iOS simulator runs record video again, and the report timeline plays the captured run video with a bottom scrubber (arrow-key stepping included).
• Experimental: Android agent-loop screenshots can be served from the live device stream (trailblaze config android-stream-screenshots, env overrides for A/B validation).
• Sensitive-args log redaction: tools can declare sensitive args (e.g. base64Content on android_writeBytesToFile), masked at the log-encode boundary so secret material stays out of persisted session logs.
• CLI/daemon quality: repeated snapshots reuse the connected device, device discovery no longer re-runs several times per command, dev rebuilds never stop a daemon with runs in flight, and CLI run polling uses an inactivity watchdog instead of a flat cap.
• Report internals: session event streams render through per-stream formatter plugins, with cross-language parity fixtures.