add Go aiscat binding

go/aiscat/README.md

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+# aiscat-go
+
+Go bindings for AIS-catcher's NMEA-to-JSON AIS decoder. The package mirrors the
+Python `aiscat` binding: a thin native bridge owns the AIS-catcher decoder, while
+Go provides ergonomic one-shot, reader, TCP, and UDP helpers.
+
+## Build Requirements
+
+- Go with cgo enabled.
+- A C++11 compiler available to cgo.
+  - Linux/macOS: `g++` or `clang++`.
+  - Windows: MSYS2 MinGW-w64 or another cgo-compatible C/C++ toolchain.
+  - This checkout was verified on Windows with Zig:
+    `CGO_ENABLED=1 CC="zig cc" CXX="zig c++" go test ./...`.
+
+This package links AIS-catcher C++ code and is GPL-3.0-or-later.
+
+## Quickstart
+
+```go
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/jvde-github/ais-catcher/go/aiscat"
+)
+
+func main() {
+	msg, err := aiscat.DecodeMap(
+		aiscat.Options{Format: aiscat.FormatDictionary},
+		[]byte("!AIVDM,1,1,,A,15MgK45P3@G?fl0E`JbR0OwT0@MS,0*4E"),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(msg["type"], msg["mmsi"], msg["lat"], msg["lon"])
+}
+```
+
+## Streaming
+
+```go
+dec, err := aiscat.NewDecoder(aiscat.Options{Format: aiscat.FormatDictionary})
+if err != nil {
+	log.Fatal(err)
+}
+defer dec.Close()
+
+dec.Feed([]byte("!AIVDM,...\r\n"))
+for {
+	msg, ok, err := dec.NextMap()
+	if err != nil {
+		log.Fatal(err)
+	}
+	if !ok {
+		break
+	}
+	fmt.Println(msg["mmsi"])
+}
+```
+
+## Formats
+
+The same format names as Python `aiscat` are available:
+
+- `FormatDictionary`
+- `FormatAnnotated`
+- `FormatJSON`
+- `FormatJSONNMEA`
+- `FormatNMEA`
+- `FormatNMEATag`
+- `FormatBinary`
+
+`Decoder.Next()` returns `map[string]any` for dictionary/annotated formats and
+`[]byte` for byte-shaped formats. Use `NextMap()` or `NextBytes()` when you want
+an explicit shape.

go/aiscat/aiscat_sources.cpp

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+// Compile the same AIS-catcher source subset used by the Python aiscat module.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../../Source/Marine/AIS.cpp"
+#include "../../Source/Marine/Message.cpp"
+#include "../../Source/Marine/NMEA.cpp"
+#include "../../Source/JSON/JSON.cpp"
+#include "../../Source/JSON/JSONAIS.cpp"
+#include "../../Source/JSON/Keys.cpp"
+#include "../../Source/JSON/Parser.cpp"
+#include "../../Source/Library/Logger.cpp"
+#include "../../Source/Utilities/Convert.cpp"
+#include "../../Source/Utilities/Helper.cpp"
+#include "../../Source/Utilities/Parse.cpp"