add: SQLite-backed structured logging with retention

Replace JSON/file logging with a logs.db (WAL) store. Thread the logger
through the encoder and metadata client for debug instrumentation of every
ffmpeg/ffprobe/opusenc invocation and OMDb/TVmaze request. API keys are
redacted before request URLs are logged. Retention defaults to 7 days,
overridable via log_retention_days in config.

internal/metadata/metadata.go

@@ -6,11 +6,13 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"regexp"
 	"strconv"
 	"strings"
 	"time"
 
+	"videnc-vibe/internal/logger"
 	"videnc-vibe/pkg/types"
 )
 
@@ -51,15 +53,49 @@ type TVMazeEpisode struct {
 type Client struct {
 	omdbAPIKey string
 	httpClient *http.Client
+	log        *logger.Logger
 }
 
-func NewClient(apiKey string) *Client {
+func NewClient(apiKey string, log *logger.Logger) *Client {
 	return &Client{
 		omdbAPIKey: apiKey,
 		httpClient: &http.Client{Timeout: 10 * time.Second},
+		log:        log,
 	}
 }
 
+// redactURL strips secret query parameters (e.g. apikey) before logging.
+func redactURL(rawURL string) string {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return rawURL
+	}
+	q := u.Query()
+	for _, k := range []string{"apikey", "api_key"} {
+		if q.Has(k) {
+			q.Set(k, "REDACTED")
+		}
+	}
+	u.RawQuery = q.Encode()
+	return u.String()
+}
+
+func (c *Client) logHTTP(label, rawURL string, status int, body []byte) {
+	if c.log == nil {
+		return
+	}
+	extra, _ := json.Marshal(struct {
+		URL    string `json:"url"`
+		Status int    `json:"status"`
+		Body   string `json:"body"`
+	}{
+		URL:    redactURL(rawURL),
+		Status: status,
+		Body:   string(body),
+	})
+	c.log.Debug(label, "", string(extra))
+}
+
 func ParseFilename(filename string) (isSeries bool, imdbID, tvmazeID, season, episode string) {
 	filename = strings.TrimSuffix(filename, ".mkv")
 
@@ -111,9 +147,9 @@ func ParseMediaType(filename string) types.MediaType {
 }
 
 func (c *Client) FetchMovieMetadata(ctx context.Context, imdbID string) (*types.Metadata, error) {
-	url := fmt.Sprintf("%s?i=%s&apikey=%s", omdbAPIURL, imdbID, c.omdbAPIKey)
+	reqURL := fmt.Sprintf("%s?i=%s&apikey=%s", omdbAPIURL, imdbID, c.omdbAPIKey)
 
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
 	if err != nil {
 		return nil, fmt.Errorf("building OMDb request: %w", err)
 	}
@@ -128,6 +164,8 @@ func (c *Client) FetchMovieMetadata(ctx context.Context, imdbID string) (*types.
 		return nil, fmt.Errorf("reading OMDb body: %w", err)
 	}
 
+	c.logHTTP("OMDb GET", reqURL, resp.StatusCode, body)
+
 	if resp.StatusCode != http.StatusOK {
 		return nil, fmt.Errorf("OMDb HTTP %d: %s", resp.StatusCode, snippet(body))
 	}
@@ -197,8 +235,8 @@ func (c *Client) FetchSeriesMetadata(ctx context.Context, tvmazeID, season, epis
 	}, nil
 }
 
-func (c *Client) fetchTVMazeJSON(ctx context.Context, url string, v interface{}) error {
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+func (c *Client) fetchTVMazeJSON(ctx context.Context, reqURL string, v interface{}) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
 	if err != nil {
 		return fmt.Errorf("build request: %w", err)
 	}
@@ -213,6 +251,8 @@ func (c *Client) fetchTVMazeJSON(ctx context.Context, url string, v interface{})
 		return fmt.Errorf("read body: %w", err)
 	}
 
+	c.logHTTP("TVmaze GET", reqURL, resp.StatusCode, body)
+
 	if resp.StatusCode != http.StatusOK {
 		return fmt.Errorf("HTTP %d: %s", resp.StatusCode, snippet(body))
 	}