fbuild-cli: promote bring-up orchestrator to first-class command

[zackees]

TL;DR

bash autoresearch <board> is FastLED's end-to-end "build + flash + reset + monitor + bring-up RPC test" pipeline. The build and flash halves use fbuild; the bring-up test half is Python that lives only on the FastLED side. As a result:

• Any other firmware project that wants the same end-to-end sanity test has to reinvent the Python wrapper.
• The split makes the boundary between "fbuild's responsibility" and "FastLED's responsibility" hard to reason about — autoresearch dips into both freely.
• New board ports require parallel updates in two repos to wire up the bring-up flow.

This issue requests promoting the bring-up orchestrator to a first-class fbuild command: fbuild bringup <board> or fbuild autoresearch <board> (name TBD).

Why this matters

FastLED bash autoresearch lpc845brk today does:

1. Build firmware → fbuild.
2. Resolve VCOM port by VID:PID → FastLED ci/util/port_utils.py.
3. Flash via pyocd → FastLED (shells out to pyocd CLI).
4. Reset → FastLED (shells out to pyocd).
5. Open monitor with DTR/RTS=True → FastLED ci/util/pyserial_monitor.py.
6. Drain boot banner → FastLED ci/autoresearch/phases.py.
7. Send JSON-RPC echo → FastLED.
8. Validate 3-way (remote_ok, log_ok, echo_ok) → FastLED.
9. Report → FastLED.

Steps 2-9 should live in fbuild. The application-specific echo sentinel (4242) and the "what does pass mean" predicate can stay as plug-ins / callbacks from the caller; the orchestration machinery is generic.

Proposed shape

$ fbuild bringup lpc845brk --rpc-method echo --rpc-payload '[4242]' --expect-result 4242
🔨 Build:       fbuild build lpc845brk          → 53.85KB / 64KB
🔌 Port:        VID:PID 16C0:0483 → COM20
📡 Flash:       pyocd flash --target lpc845    → 60416 bytes / 3.10 kB/s
🔄 Reset:       sw reset                        → resumed
👂 Monitor:     COM20 @ 115200, DTR=True       → 8s drain
📨 RPC:         {"method":"echo","params":[4242]}
                {"result":4242}                  ✓
✅ BRING-UP PASSED  (3.7 s)

FastLED's bash autoresearch becomes a one-line shell that calls fbuild bringup with the right per-board defaults. Per-board defaults live in board JSON (echo method, sentinel, expected-result predicate).

Acceptance criteria

• fbuild bringup subcommand exists in fbuild-cli.
• Pluggable RPC method / payload / expected-result via CLI flags.
• Per-board defaults loaded from board JSON bringup.{method, payload, expected_result}.
• FastLED's bash autoresearch migrated to a thin wrapper.
• Same output shape on success and failure (3-way remote_ok / log_ok / echo_ok tuple).

Refs

• FastLED/fbuild#686 — serial_probe CLI. Bring-up uses the same primitives.
• FastLED/fbuild#687 — BoardFamily. Bring-up consults it for reset method.
• FastLED/fbuild#691 — handoff timing. Bring-up consumes it.
• FastLED/FastLED#3339 — the LPC bring-up incident. Demonstrates how scattered the responsibility was; this issue consolidates it.

Filed from the audit fan-out on FastLED/FastLED#3339.