refactor: chats method shebangs; drop chats index (D14).

Parsers and commands live in internal/chats. bin/chats/{sync,import,facts,apply}.go
are tagged shebang mains. Brain ingest is not a chats command.

bin/chats/import.go

@@ -0,0 +1,20 @@
+//usr/bin/env go run -tags=chats_import "$0" "$@"; exit
+//go:build chats_import
+//
+// bin/chats/import.go - JSONL → markdown under var/chats/md/.
+//
+//	./bin/chats/import.go
+//
+// Conversion only. Brain ingest is bin/brain/index.go, not this command.
+// NOTE: never run `gofmt -w` on this file — it breaks the shebang.
+package main
+
+import (
+	"os"
+
+	"github.com/eSlider/2dph/internal/chats"
+)
+
+func main() {
+	os.Exit(chats.RunImport(os.Args[1:]))
+}