amipilot v0.3

The wire and the host client: the same command set the ARexx port
speaks, now reachable from a host machine — no ARexx interpreter or
even a Workbench session on the Amiga side needed to drive it.

What's in 0.3:

• The wire protocol: a length-prefixed line protocol over
  serial.device, with no JSON anywhere — requests are the exact same
  command grammar the ARexx port already parses, responses are
  RC <code> <byte-count> followed by exactly that many payload
  bytes, binary-safe with zero escaping. A VERSION handshake
  reports the server version, the protocol number, and which verbs
  are stable vs. experimental. See the
  Wire Protocol
  reference.
• AmiPilotServer SERIAL: the commodity now optionally carries its
  whole verb set over serial.device (SERDEVICE/SERUNIT/BAUD to
  configure), alongside its existing ARexx port — the same dispatch
  serves both, so results are identical either way.
• The host Python client (pip install -e host/ from the source
  tree): a transport-level WireClient, and Amipilot — the
  Pythonic object API (tree()/click()/type()/get_text()/
  manifest(), plus @name locator forms) that raises typed
  exceptions instead of requiring manual RC checks.
• amipilot dump <window>: the host half of "the inspector" —
  connects and prints a window's gadget tree, either in the same
  format AmiInspect prints or as ready-to-paste # name = <id>
  suggestions for a quirk profile.
• A pytest plugin: the amipilot fixture boots a configured
  Copperline (or real-hardware-adjacent) session and hands a test a
  connected client — session-scoped, and it skips cleanly rather
  than failing when no emulator config is set up. This delivers the
  phase's actual release gate: a host pytest test types into a
  field, reads it back, clicks a button, and asserts the window
  closed — driven entirely from the host, with Copperline booted by
  the test itself.

Known gaps, tracked as real follow-up work, not silently accepted:

• TCP transport (for real hardware or an emulator with no serial
  bridge) is phase 0.4 scope, along with program launch, the file
  API, menus, and drag.
• No wait/expectation primitives yet (click that waits for an
  expected change, timeouts) — a script still adds its own polling.
• The wire connects host-to-Amiga only; the Amiga dialing out to a
  configured host (useful behind NAT) is a considered future
  addition, not yet built.
• No public CI on-target run yet, same reason as 0.1/0.2:
  make test-target needs a machine-specific Workbench install CI
  doesn't have.

See the full changelog
for more detail.