ci(release): ship both plain and self-contained (_s101) binaries

Mirror `make xbuild`: two GoReleaser builds per platform — a plain binary (no
catalogue, needs --s101 at runtime) and an _s101 binary (-tags embed_s101,
self-contained). Two archive sets, the embedded one suffixed _s101. Verified via
snapshot dry-run: plain reports "embedded: false", _s101 "embedded: true".

Only the _s101 variant redistributes the IHO catalogue; README + notices updated
to describe both.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

Author: beetlebugorg

.goreleaser.yaml

@@ -8,46 +8,50 @@ before:
   hooks:
     - go mod tidy
 
+# Two builds per platform, mirroring `make xbuild`:
+#   - plain: needs `--s101 <dir>` at runtime (no IHO content embedded)
+#   - _s101: self-contained, embeds the S-101 Portrayal + Feature Catalogues
+#     (the release workflow runs `make sync-s101` first to populate the embed dir).
+#     That catalogue is IHO material with no declared license — see
+#     THIRD-PARTY-NOTICES.md.
+# Shared settings live in an anchor so the two only differ by the embed tag.
 builds:
   - id: chartplotter
     main: ./cmd/chartplotter
     binary: chartplotter
-    env:
-      - CGO_ENABLED=0
-    # Self-contained: embed the S-101 Portrayal + Feature Catalogues (the release
-    # workflow syncs them into internal/engine/s101catalog/catalog/ first). That
-    # catalogue is IHO material with no declared license — see THIRD-PARTY-NOTICES.md.
-    tags:
-      - embed_s101
-    flags:
-      - -trimpath
-    ldflags:
-      - -s -w -X main.version={{ .Version }}
-    goos:
-      - linux
-      - darwin
-      - windows
-    goarch:
-      - amd64
-      - arm64
+    env: [CGO_ENABLED=0]
+    flags: [-trimpath]
+    ldflags: ["-s -w -X main.version={{ .Version }}"]
+    goos: [linux, darwin, windows]
+    goarch: [amd64, arm64]
     # No 32-bit / niche targets: the tile baker is memory-hungry.
+  - id: chartplotter-s101
+    main: ./cmd/chartplotter
+    binary: chartplotter
+    env: [CGO_ENABLED=0]
+    tags: [embed_s101]
+    flags: [-trimpath]
+    ldflags: ["-s -w -X main.version={{ .Version }}"]
+    goos: [linux, darwin, windows]
+    goarch: [amd64, arm64]
 
 archives:
   - id: chartplotter
+    ids: [chartplotter]
+    formats: [tar.gz]
+    format_overrides:
+      - goos: windows
+        formats: [zip]
+    name_template: "{{ .ProjectName }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}"
+    files: [README.md, LICENSE, THIRD-PARTY-NOTICES.md]
+  - id: chartplotter-s101
+    ids: [chartplotter-s101]
     formats: [tar.gz]
-    # Windows gets a .zip instead of a tarball.
     format_overrides:
       - goos: windows
         formats: [zip]
-    name_template: >-
-      {{ .ProjectName }}_
-      {{- .Version }}_
-      {{- .Os }}_
-      {{- .Arch }}
-    files:
-      - README.md
-      - LICENSE
-      - THIRD-PARTY-NOTICES.md
+    name_template: "{{ .ProjectName }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}_s101"
+    files: [README.md, LICENSE, THIRD-PARTY-NOTICES.md]
 
 checksum:
   name_template: "checksums.txt"

README.md

@@ -78,9 +78,13 @@ static binary** for any platform with `GOOS`/`GOARCH` and nothing else to instal
 
 Download an archive for your platform from the
 [**Releases**](https://github.com/beetlebugorg/chartplotter/releases) page, extract it,
-and put `chartplotter` on your `PATH`. Release binaries are self-contained — they
-embed the S-101 catalogue and run with no extra files. (That catalogue is IHO
-material; see [THIRD-PARTY-NOTICES.md](THIRD-PARTY-NOTICES.md).)
+and put `chartplotter` on your `PATH`. Each platform ships two builds:
+
+- **`…_s101`** — self-contained: embeds the S-101 catalogue, runs with no extra
+  files. (That catalogue is IHO material; see
+  [THIRD-PARTY-NOTICES.md](THIRD-PARTY-NOTICES.md).)
+- **plain** — needs `--s101 <PortrayalCatalog dir>` at runtime, pointing at your
+  own copy of the catalogue.
 
 ### With go install
 

THIRD-PARTY-NOTICES.md

@@ -89,10 +89,11 @@ How chartplotter handles them:
   (`internal/engine/s101catalog/catalog/`) and synced from an external copy at
   build time (`make sync-s101`), so the repository itself does not redistribute
   IHO material.
-- **Embedded in release binaries.** The release workflow clones the two IHO repos
-  above and builds with `-tags embed_s101`, so the published binaries are
-  self-contained and **do** redistribute the catalogue. A plain `go build`
-  (without the tag) omits it and requires `--s101 <dir>` at runtime.
+- **Embedded only in the `_s101` release binaries.** Each release ships two builds
+  per platform: a plain binary (no catalogue; needs `--s101 <dir>` at runtime) and
+  an `_s101` binary built with `-tags embed_s101`. The release workflow clones the
+  two IHO repos above so the `_s101` build embeds the catalogue — only that variant
+  **redistributes** IHO material.
 
 Because the IHO repositories declare no license, the right to redistribute this
 material in release binaries is **unconfirmed**. The IHO copyright and