Initial template: release pipeline + PORTING.md + init helper

What lands in any repo created from this template:
- .gitea/workflows/release.yml — canonical Gitea-Actions release pipeline
  (tag-triggered, curl-based publish, per-asset failure tolerance)
- tools/build_zip.sh — git-archive per addon folder, multi-addon bundle
- tools/init_from_upstream.sh — one-shot squash-import of upstream tree
  into <AddonFolder>/ at the repo root
- PORTING.md — full CoA-compat bug-pattern checklist (Retail-only
  globals, FileDataIDs, hardcoded class lists, StaticPopup race,
  .tga textures, Minimap mask, CLEU arg positions, Ace3 sweep, etc.)
- README.md — quick-start backport guide
- standard .gitignore (incl dist/) + .gitattributes (* -text)

tools/init_from_upstream.sh

@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# init_from_upstream.sh — bootstrap a new Exiles addon fork from upstream.
+#
+# Usage:
+#   tools/init_from_upstream.sh <upstream-url> <AddonFolderName> [upstream-branch]
+#
+# Example:
+#   tools/init_from_upstream.sh https://github.com/Ascension-Addons/CallToArms CallToArms
+#
+# What it does:
+#   1. Adds `upstream` remote and fetches it.
+#   2. Squash-imports the upstream tree at the named branch (default master/main)
+#      into <AddonFolderName>/ at the repo root.
+#   3. Leaves you with a single staged commit you review and finalise.
+#
+# What it does NOT do:
+#   - Push anything.
+#   - Tag anything.
+#   - Modify the upstream history (it's a squash import, not a merge).
+#
+# After running, verify with:
+#   bash tools/build_zip.sh
+#   unzip -l dist/<AddonFolderName>.zip | head -5
+# then `git commit --amend` if you want to edit the message, push,
+# and tag <upstream-version>-coa.1 to trigger the first release.
+set -euo pipefail
+
+if [ "$#" -lt 2 ] || [ "$#" -gt 3 ]; then
+    echo "usage: $0 <upstream-url> <AddonFolderName> [upstream-branch]" >&2
+    exit 2
+fi
+
+upstream_url=$1
+folder=$2
+branch=${3:-}
+
+if [ -d "$folder" ]; then
+    echo "refusing to overwrite existing folder $folder/" >&2
+    exit 1
+fi
+
+if ! git remote get-url upstream >/dev/null 2>&1; then
+    git remote add upstream "$upstream_url"
+else
+    git remote set-url upstream "$upstream_url"
+fi
+
+echo "==> fetching upstream"
+git fetch --tags upstream
+
+if [ -z "$branch" ]; then
+    # Try master, then main.
+    if git rev-parse --verify "upstream/master" >/dev/null 2>&1; then
+        branch=master
+    elif git rev-parse --verify "upstream/main" >/dev/null 2>&1; then
+        branch=main
+    else
+        echo "couldn't find upstream/master or upstream/main; pass branch explicitly" >&2
+        exit 1
+    fi
+fi
+echo "==> importing tree from upstream/$branch into $folder/"
+
+# Extract upstream tree into a temporary worktree-like dir, then move into folder.
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' EXIT
+git archive "upstream/$branch" | tar -x -C "$tmp"
+mkdir -p "$folder"
+# rsync preserves dotfiles; --exclude keeps obvious noise out.
+rsync -a --exclude '.git/' --exclude '.github/' --exclude '.gitea/' \
+      --exclude '.idea/' --exclude '.vscode/' --exclude '.DS_Store' \
+      "$tmp"/ "$folder"/
+
+git add "$folder"
+upstream_sha=$(git rev-parse "upstream/$branch")
+upstream_short=$(git rev-parse --short "upstream/$branch")
+git commit -m "Import $folder from upstream@$upstream_short
+
+upstream: $upstream_url
+branch:   $branch
+commit:   $upstream_sha"
+
+cat <<EOF
+
+==> done. next steps:
+    1. bash tools/build_zip.sh
+    2. unzip -l dist/$folder.zip | head -5
+       (expect first entry: $folder/)
+    3. git push origin master
+    4. Read $folder/$folder.toc — look for the version string.
+       Tag with <upstream-version>-coa.1, e.g.:
+         git tag -a 1.2.3-coa.1 -m "first Exiles release"
+         git push origin 1.2.3-coa.1
+       The release workflow picks it up and publishes
+       https://git.sub-net.at/Exiles/<this-repo>/releases/tag/<tag>.
+
+    The upstream remote stays configured so future rebases / re-imports
+    are one-line: \`git fetch upstream && ...\`.
+EOF