feat: in-process HTTP search; /get /stats /audit /ingest.

bin/brain/serve.go (ladybug tags) calls internal/brain instead of exec.
HTTP tests inject a fake API so CI stays cgo-free. ExecSearcher remains
the fallback when the binary is built without system_ladybug.

bin/brain/serve.go

@@ -1,18 +1,20 @@
-//usr/bin/env go run -tags=brain_serve "$0" "$@"; exit
-//go:build brain_serve
+//usr/bin/env go run -tags=brain_serve,system_ladybug "$0" "$@"; exit
+//go:build brain_serve && cgo && system_ladybug
 //
-// bin/brain/serve.go - HTTP API for the 2dph brain.
+// bin/brain/serve.go - HTTP API (in-process ladybug search).
 //
 //	KB_ROOT=/path/to/2dph ./bin/brain/serve.go
-//	KB_SEARCH_CMD=... KB_WORKERS=4 KB_PORT=8630 ./bin/brain/serve.go
+//	KB_WORKERS=4 KB_PORT=8630 ./bin/brain/serve.go
 //
-// Default search backend is var/bin/brain-search (Go), not Python.
+// Needs CGO + libladybug (same as bin/brain/search.go).
 // NOTE: never run `gofmt -w` on this file — it breaks the shebang.
 package main
 
 import (
+	"log"
 	"os"
 
+	"github.com/eSlider/2dph/internal/brain"
 	"github.com/eSlider/2dph/internal/httpapi"
 )
 
@@ -22,5 +24,8 @@ func main() {
 			os.Setenv("KB_ROOT", wd)
 		}
 	}
-	httpapi.Run()
+	if err := brain.Ready(); err != nil {
+		log.Fatal(err)
+	}
+	httpapi.Run(brain.HTTP{})
 }

bin/brain/serve_exec.go

@@ -0,0 +1,20 @@
+//go:build brain_serve && !system_ladybug
+//
+// Fallback serve when ladybug cgo is not in the build (CI / tags=brain_serve).
+// Production shebang is serve.go (in-process).
+package main
+
+import (
+	"os"
+
+	"github.com/eSlider/2dph/internal/httpapi"
+)
+
+func main() {
+	if os.Getenv("KB_ROOT") == "" {
+		if wd, err := os.Getwd(); err == nil {
+			os.Setenv("KB_ROOT", wd)
+		}
+	}
+	httpapi.Run(nil)
+}