Serve the CI pipeline from the update server

This repo still carried the inline pipeline from before the config
extension, including the droparea SSH upload that predates
/build/upload. That step asked for a droparea_ssh_password secret which
no longer exists, so every run failed before reaching the publish.

The marker config gets the same pipeline every other TIC-80 repo gets,
and the artifacts go through /build/upload and /build/publish.

The Makefile keeps its ci-upload target and DROPAREA_* variables; they
are now unused by CI and can go in a separate pass.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.woodpecker.yaml

@@ -0,0 +1,2 @@
+# The CI pipeline is served by the update server: GET /build/config?platform=tic80
+platform: tic80

.woodpecker.yml

@@ -1,43 +0,0 @@
-steps:
-  - name: version
-    image: alpine
-    commands:
-      - 'apk add --no-cache make'
-      - 'make ci-version'
-
-  - name: build
-    image: git.teletypegames.org/build/tic80pro:latest
-    environment:
-      XDG_RUNTIME_DIR: /tmp
-    commands:
-      - 'make ci-export'
-
-  - name: binaries
-    image: git.teletypegames.org/build/tic80pro:latest
-    environment:
-      XDG_RUNTIME_DIR: /tmp
-    commands:
-      - 'make ci-binaries'
-
-  - name: artifact
-    image: alpine
-    environment:
-      DROPAREA_HOST: vps.teletype.hu
-      DROPAREA_PORT: 2223
-      DROPAREA_TARGET_PATH: /home/drop
-      DROPAREA_USER: drop
-      DROPAREA_SSH_PASSWORD:
-        from_secret: droparea_ssh_password
-    commands:
-      - 'apk add --no-cache make openssh-client sshpass'
-      - 'make ci-upload'
-
-  - name: update
-    image: alpine
-    environment:
-      UPDATE_SERVER: https://teletypegames.org
-      UPDATE_SECRET:
-        from_secret: update_secret_key
-    commands:
-      - 'apk add --no-cache make curl'
-      - 'make ci-update'