fix: hyperguild brain write requires wing/hall, not legacy type/slug (#79)

Removes brain_write legacy domain/type/knowledge-path params (ADR-0012) and migrates the previously-missed cmd/hyperguild CLI caller (hyperguild brain write) from <type> <slug> to <wing> <hall> <slug>, fixing a 100%% regression the first review round caught. Adds TestWrite_CLIPayloadRoundTrips exercising the real Handler.Write over HTTP to pin the wire contract.

Closes #79.

Co-authored-by: Mathias <mthbqv@gmail.com>

cmd/hyperguild/brain.go

@@ -60,13 +60,14 @@ func runBrainWrite(ctx context.Context, args []string, stdin io.Reader, stdout,
 	if err := fs.Parse(args); err != nil {
 		return fmt.Errorf("parse flags: %w", err)
 	}
-	if fs.NArg() < 2 {
-		return errors.New("type and slug required (e.g. brain write knowledge my-slug)")
+	if fs.NArg() < 3 {
+		return errors.New("wing, hall and slug required (e.g. brain write homelab facts my-slug)")
 	}
-	kind := fs.Arg(0)
-	slug := fs.Arg(1)
+	wing := fs.Arg(0)
+	hall := fs.Arg(1)
+	slug := fs.Arg(2)
 
-	res, err := newBrainClient().Write(ctx, kind, slug, stdin)
+	res, err := newBrainClient().Write(ctx, wing, hall, slug, stdin)
 	if err != nil {
 		return err
 	}