feat(02-02): record manifest route cases and report coverage

Drive ordered route cases through RecordFlow, resume in batches of
15, and print recorded/passing/failing/unrecorded coverage.

Co-authored-by: Cursor <cursoragent@cursor.com>

tide/flow.go

@@ -1,8 +1,11 @@
 package tide
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"fmt"
 	"net/http"
+	"os"
 	"path/filepath"
 	"strings"
 )
@@ -84,6 +87,7 @@ type ReplayConfig struct {
 	Client  *http.Client
 	MaxBody int64
 	Store   *Store
+	BaseDir string
 }
 
 // Result is the outcome of replaying a flow.
@@ -169,6 +173,30 @@ func validateFlow(flow Flow) error {
 	return nil
 }
 
+func materializeSidecar(base string, resp *Response) error {
+	if resp == nil || resp.BodyFile == "" {
+		return nil
+	}
+	if err := validateSidecar(resp.BodyFile); err != nil {
+		return err
+	}
+	path := resp.BodyFile
+	if base != "" {
+		path = filepath.Join(base, resp.BodyFile)
+	}
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		return fmt.Errorf("tide: read body_file %s: %w", resp.BodyFile, err)
+	}
+	sum := sha256.Sum256(raw)
+	got := hex.EncodeToString(sum[:])
+	if resp.SHA256 != "" && !strings.EqualFold(got, resp.SHA256) {
+		return fmt.Errorf("tide: body_file %s digest mismatch", resp.BodyFile)
+	}
+	resp.Body = Body(raw)
+	return nil
+}
+
 func validateSidecar(path string) error {
 	if path == "" {
 		return nil