feat(ingestion): implement brain_ingest_raw MCP tool

Wraps pipeline.RunRaw directly. Same dry-run semantics as the HTTP
/ingest-raw endpoint. Test exercises a single concept page; asserts
returned path and that no file is written under dry_run.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ingestion/internal/mcp/handlers.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/search"
 )
 
@@ -122,3 +123,35 @@ func (s *Server) brainWrite(ctx context.Context, args json.RawMessage) (json.Raw
 	}
 	return json.Marshal(map[string]string{"path": relPath})
 }
+
+type brainIngestRawArgs struct {
+	Source string             `json:"source"`
+	Pages  []pipeline.RawPage `json:"pages"`
+	DryRun bool               `json:"dry_run,omitempty"`
+}
+
+func (s *Server) brainIngestRaw(ctx context.Context, args json.RawMessage) (json.RawMessage, error) {
+	var a brainIngestRawArgs
+	if err := json.Unmarshal(args, &a); err != nil {
+		return nil, fmt.Errorf("parse args: %w", err)
+	}
+	if a.Source == "" {
+		return nil, fmt.Errorf("source is required")
+	}
+	if len(a.Pages) == 0 {
+		return nil, fmt.Errorf("pages must be non-empty")
+	}
+	result, err := pipeline.RunRaw(s.brainDir, a.Source, a.Pages, a.DryRun)
+	if err != nil {
+		return nil, fmt.Errorf("ingest: %w", err)
+	}
+	pages := result.Pages
+	if pages == nil {
+		pages = []string{}
+	}
+	warnings := result.Warnings
+	if warnings == nil {
+		warnings = []string{}
+	}
+	return json.Marshal(map[string]any{"pages": pages, "warnings": warnings})
+}