port: the container agent answers the questions, it does not build the port

Corrects the split I got wrong in b5a1938. The container is for reverse
engineering, now focused on the menu port; a SEPARATE agent builds the port from
its investigation results. My previous version had the container agent writing
the exporter and the Godot project, which is not the intent.

This lands on the research/engineering line that was already in the estimate:
the container agent takes the research half, the port agent the engineering half.

docs/port/MISSION.md is now a list of open QUESTIONS (Q1-Q9) rather than build
milestones, ordered by what blocks the port earliest -- the keyframe time unit,
which build is which screen state, paint order for the six screens, button ->
GamePart, navigation semantics, the boot sequence driver, transitions, menu
audio bindings, and video binding. Each is done when a written result with
evidence exists, not when something compiles. S1, the Ready Room probe, stays
gated at one iteration and a go/no-go.

Most of these are BEHAVIOUR questions -- timing, transitions, what a d-pad press
does at the end of a list -- so the mission and the loop prompt both push hard
on measuring the oracle rather than reasoning from the file.

docs/port/FORMAT.md is deleted. The export schema is the port agent's design and
was not mine to specify. It is replaced by docs/port/HANDOFF.md, the single page
the port agent reads: a status table, what is already settled and can be relied
on today, and the facts that will trip the port up (the WMV3/WMA Pro intro, the
Static.slb size over-declaration, the voice-vs-music downmix, JNGL_001).

The derived/authored idea survives as the thing it always was -- a finding, not
a design. Every answer must be classified DECODED, MEASURED or UNDECODABLE-with-
reach, and never a fourth thing, because measured and undecodable both mean the
port agent is authoring that value and has to know it. Labelling a guess as a
decode would put it into the port wearing the badge of a measurement.

Reverts the Godot install from the RE container, its AGENT.md section, and the
export/ gitignore entry -- none of that belongs on this side of the wall.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docker/agent/Dockerfile

@@ -68,26 +68,6 @@ RUN for t in clang clang++ lld ld.lld llvm-ar llvm-ranlib llvm-nm clang-cpp; do
 # Python consumer to protect, so installing into it is the honest simple option.
 RUN pip3 install --no-cache-dir --break-system-packages duckdb
 
-# ── Godot 4 ──────────────────────────────────────────────────────────────────
-# The port's runtime (docs/port/MISSION.md). Two binaries, deliberately:
-#
-#   godot           the editor/windowed build, run under Xvfb, for screenshots
-#                   that can be diffed against `sylpheed-cli screen render`
-#   godot-headless  --headless, for script-only checks that need no display
-#
-# The official builds are self-contained binaries, not a package, so they are
-# fetched rather than apt-installed. Pinned: an engine version bump changes
-# rendering, and this project compares screenshots against a reference renderer.
-ARG GODOT_VERSION=4.3
-RUN cd /tmp \
-    && curl -fsSLO "https://github.com/godotengine/godot/releases/download/${GODOT_VERSION}-stable/Godot_v${GODOT_VERSION}-stable_linux.x86_64.zip" \
-    && unzip -q "Godot_v${GODOT_VERSION}-stable_linux.x86_64.zip" \
-    && mv "Godot_v${GODOT_VERSION}-stable_linux.x86_64" /usr/local/bin/godot \
-    && chmod +x /usr/local/bin/godot \
-    && printf '#!/bin/sh\nexec /usr/local/bin/godot --headless "$@"\n' > /usr/local/bin/godot-headless \
-    && chmod +x /usr/local/bin/godot-headless \
-    && rm -f "Godot_v${GODOT_VERSION}-stable_linux.x86_64.zip"
-
 # ── Node + Claude Code ───────────────────────────────────────────────────────
 RUN curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
     && apt-get install -y --no-install-recommends nodejs \