feat(cli): devagent up / down — one-command setup and driver start (kills the SELFBUILD_* tribal knowledge)

[linhdmn]

Problem

Starting the factory today needs tribal knowledge, not a command:

• the loop driver reads config from the environment only (SELFBUILD_*, internal/loopdriver/config.go:240); nothing reads devagent.json for it, so every knob is an export;
• DevagentBin defaults to the bare name devagent (config.go:79), so a checkout that only ever builds ./devagent-go (make build) runs a stale or missing CLI for pane-run/task/preflight/sync-docs;
• the start path is make loop-start in the repo (nohup + pgrep) or a hand-made hub job, and the selfbuild/state branch plus the selfbuild issue label are assumed to exist;
• devagent create still bakes Node-era argv into its LaunchAgents (dist/src/cli.js at internal/pipeline/create.go:164, scripts/build-loop.sh at :193) — both paths are gone with the retired tree.

Requested change

One lifecycle command per direction:

• devagent up — verify → seed → start, then report:
  1. prerequisite gate (reuse commands.RunDoctor/RunInit checks: git origin + gh auth + worker CLI), aborting with the plain-language fix line;
  2. config + state dirs (.selfbuild/{research,goals,logs}, .devagent/queue), selfbuild issue label ensured;
  3. PRD intake (feat(prd-intake): operator PRD checkboxes become loop work (the value lane #355 asks for) #370) so the lane starts non-empty;
  4. daemon start when down (:7788) and the loop driver detached (setsid + .selfbuild/logs/driver.log + pid file), or --foreground to run it in this terminal;
  5. a final "what is running / where to look / next action" card.
• devagent down — stop exactly the processes up started (pid files, never a blind pkill -f).
• Fix devagent create's plist argv to the Go self-executable (createSelfExePath(), :216) and devagent loop, dropping the dist/src/cli.js and scripts/build-loop.sh entries.

Acceptance

• devagent up on a clean checkout with only make build done starts a supervised-free driver and prints pid + log path + queue depth; a second up is idempotent (reports the live pid, starts nothing).
• devagent down leaves no devagent-go loop/daemon process behind and reports what it stopped.
• devagent create --dry-run emits plists whose ProgramArguments contain no deleted paths.

[linhdmn]

Implemented in the working tree 2026-09-14 (labels adjusted so the loop does not re-pick it before this lands).

• internal/prdintake + internal/loopdriver/intake.go + devagent prd-intake + internal/commands/updown.go (up/down) + internal/scout/run.go (live FR-SCOUT-01 cycle).
• Verified: gofmt/go vet/golangci-lint clean, full go test ./... green, and live smoke runs — an open - [ ] item in a scratch repo's docs/PRD.md was ingested, claimed by the next iteration, and published as .selfbuild/goals/loop-1.md; up proved the detached driver (holds the loop lock, iteration 2, phase queue-empty) and failed it with the cause (exited: max iterations reached) when the driver halted; down stopped the recorded pid and left no process behind; devagent scout --once --dry-run previews a cycle with no AI call and no writes.