merge the Godot port's history into the monorepo

Brought in with a subtree merge rather than a copy, so the port's 31 commits
survive as history rather than arriving as one anonymous import. Landed under
godot-import/ and moved into the final layout in the next commit, which keeps
git's rename detection able to follow each file across the move.

godot-import/docs/loop-task.md

@@ -0,0 +1,93 @@
+Build the Godot menu port, one milestone at a time.
+
+## Your objective
+
+`docs/MISSION.md` — read it every iteration. It defines the milestones P0…P7 and
+the gate each must pass, the wall between the exporter and Godot, and the
+derived/authored split.
+
+**You do not reverse engineer.** A separate container agent does that, in the
+Syplheed-Reborn repository, mounted read-only at `/reborn`. You have no emulator
+and no oracle, so a guess of yours is indistinguishable from a fact and will be
+believed later. If you need an answer the disc has not given you, write it in
+`docs/BLOCKED.md` and move to another milestone.
+
+## Read these first, every iteration
+
+1. `docs/MISSION.md` — milestones, gates, scope.
+2. `/reborn/docs/port/HANDOFF.md` — **the contract.** What is decoded, what was
+   measured off the running game, and what is known undecodable.
+
+   **It is a live read-only mount of the RE agent's working tree**, so it updates
+   itself and there is nothing to pull — `git -C /reborn pull` cannot work (the
+   mount is read-only) and should not: it would move another agent's checkout.
+   `git -C /reborn log -1` shows where they are.
+
+   Because it is live, **it can move under you mid-iteration.** Anything you
+   copied out of it earlier — `docs/BLOCKED.md` especially — may already be
+   stale. Re-check it against HANDOFF before trusting it.
+3. `docs/FORMAT.md` — the open format. It is versioned and it is yours to
+   revise, but a change is a deliberate act with a version bump.
+4. `docs/BLOCKED.md` — what you are waiting on, so you do not re-discover it.
+
+`/reborn/docs/re/disc-atlas.html` maps how the assets reference each other.
+
+## Each iteration
+
+1. **Pick the lowest unfinished milestone.** If it is blocked on an RE answer,
+   record that in `docs/BLOCKED.md` and take the next one that is not.
+2. **Build the smallest thing that reaches its gate.** The gate is an artifact —
+   a validating JSON file, a screenshot, a clickable build — never "it compiles".
+3. **Keep derived and authored apart.** `export/` is regenerated wholesale and
+   never hand-edited. A fix you are tempted to make there belongs in the exporter
+   or in `authored/`, and every `authored/` entry carries a `why`.
+4. **Write down what you decided**, in `docs/`. A decision that lives only in
+   your context is lost when the container dies.
+5. **Commit** to `auto/<topic>`, one logical change per commit.
+6. **Publish**: `push-work`. Every iteration that produced a commit.
+7. **Say plainly what you did not settle**, and stop.
+
+## Hard rules
+
+* **Never commit game assets.** `export/` is gitignored and generated from the
+  user's own disc. Code, schemas, `authored/` mappings and docs only.
+* **No Rust in `port/`, no GDExtension.** If Godot cannot read something, the
+  exporter emits it differently.
+* **Do not vendor or reimplement `sylpheed-formats`** — it is pinned by revision.
+  In particular do not reimplement media assembly: `sylpheed_formats::media`
+  already handles segment-spanning entries, multi-sub-wave banks and the
+  continuous cutscene-voice stream, and that last one is the easiest thing here
+  to get subtly wrong.
+* **`/reborn` is READ-ONLY.** Never commit there, never edit it. It belongs to
+  the other agent and you share no working tree with it.
+* **Never commit to `main`**, never rebase a shared branch, never rewrite history.
+* **Do not adopt a runtime dependency on your own authority.** Propose it.
+
+## Verifying
+
+* `sylpheed-cli screen render` (built from `/reborn`) is the reference renderer.
+  When Godot draws a screen, diff against the CLI's composite of the same build.
+  Where they disagree, one of them is wrong — say which, and why, rather than
+  tuning until they match.
+* Godot runs headless (`godot-headless`), and windowed under Xvfb with
+  `screenshot` for a capture.
+* A regenerated `export/` that comes out byte-identical is strong evidence a
+  change was additive. When it does change, check that every diff line pairs.
+
+## Publishing
+
+`push-work` pushes the current branch to origin. It refuses anything that is not
+`auto/*` and never force-pushes, so the consolidated line stays a human's
+decision. Run it **every iteration that produced a commit** — not at the end of
+some longer arc, which is exactly when a container dies.
+
+If it reports no credentials, say so in your reply and continue working. Do not
+improvise another route out.
+
+## Pacing
+
+One milestone step plus its write-up is a good iteration; a marathon is not. Stop
+with a clean commit, a push, and an honest list of what is still open.
+
+The loop runs on a fixed interval set by the harness, so you do **not** need to
+arm the next wakeup yourself. Spend that attention on the write-up instead.