feat: implement file upload handler and related functionality

- Added file upload handler to process both multipart and raw file uploads.
- Implemented parsing logic for upload requests, including handling file metadata.
- Introduced SaveFileDecodedInput structure for handling decoded file uploads.
- Created unit tests for file upload parsing and validation.

feat: add metadata retry configuration and functionality

- Introduced MetadataRetryConfig to the application configuration.
- Implemented MetadataRetryer to handle retrying metadata extraction for thoughts.
- Added new tool for retrying failed metadata extractions.
- Updated thought metadata structure to include status and timestamps for metadata processing.

fix: enhance metadata normalization and error handling

- Updated metadata normalization functions to track status and errors.
- Improved handling of metadata extraction failures during thought updates and captures.
- Ensured that metadata status is correctly set during various operations.

refactor: streamline file saving logic in FilesTool

- Refactored Save method in FilesTool to utilize new SaveDecoded method.
- Simplified project and thought ID resolution logic during file saving.

internal/app/files.go

@@ -0,0 +1,112 @@
+package app
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"mime"
+	"net/http"
+	"strings"
+
+	"git.warky.dev/wdevs/amcs/internal/tools"
+)
+
+const maxUploadBytes = 50 << 20
+
+func fileUploadHandler(files *tools.FilesTool) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			w.Header().Set("Allow", http.MethodPost)
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+
+		r.Body = http.MaxBytesReader(w, r.Body, maxUploadBytes)
+
+		in, err := parseUploadRequest(r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		out, err := files.SaveDecoded(r.Context(), nil, in)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusCreated)
+		_ = json.NewEncoder(w).Encode(out)
+	})
+}
+
+func parseUploadRequest(r *http.Request) (tools.SaveFileDecodedInput, error) {
+	contentType := r.Header.Get("Content-Type")
+	mediaType, _, _ := mime.ParseMediaType(contentType)
+
+	if strings.HasPrefix(mediaType, "multipart/form-data") {
+		return parseMultipartUpload(r)
+	}
+
+	return parseRawUpload(r)
+}
+
+func parseMultipartUpload(r *http.Request) (tools.SaveFileDecodedInput, error) {
+	if err := r.ParseMultipartForm(maxUploadBytes); err != nil {
+		return tools.SaveFileDecodedInput{}, err
+	}
+
+	file, header, err := r.FormFile("file")
+	if err != nil {
+		return tools.SaveFileDecodedInput{}, errors.New("multipart upload requires a file field named \"file\"")
+	}
+	defer file.Close()
+
+	content, err := io.ReadAll(file)
+	if err != nil {
+		return tools.SaveFileDecodedInput{}, err
+	}
+
+	return tools.SaveFileDecodedInput{
+		Name:      firstNonEmpty(r.FormValue("name"), header.Filename),
+		Content:   content,
+		MediaType: firstNonEmpty(r.FormValue("media_type"), header.Header.Get("Content-Type")),
+		Kind:      r.FormValue("kind"),
+		ThoughtID: r.FormValue("thought_id"),
+		Project:   r.FormValue("project"),
+	}, nil
+}
+
+func parseRawUpload(r *http.Request) (tools.SaveFileDecodedInput, error) {
+	content, err := io.ReadAll(r.Body)
+	if err != nil {
+		return tools.SaveFileDecodedInput{}, err
+	}
+
+	name := firstNonEmpty(
+		r.URL.Query().Get("name"),
+		r.Header.Get("X-File-Name"),
+	)
+	if strings.TrimSpace(name) == "" {
+		return tools.SaveFileDecodedInput{}, errors.New("raw upload requires a file name via query param \"name\" or X-File-Name header")
+	}
+
+	return tools.SaveFileDecodedInput{
+		Name:      name,
+		Content:   content,
+		MediaType: r.Header.Get("Content-Type"),
+		Kind:      firstNonEmpty(r.URL.Query().Get("kind"), r.Header.Get("X-File-Kind")),
+		ThoughtID: firstNonEmpty(r.URL.Query().Get("thought_id"), r.Header.Get("X-Thought-Id")),
+		Project:   firstNonEmpty(r.URL.Query().Get("project"), r.Header.Get("X-Project")),
+	}, nil
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, value := range values {
+		if strings.TrimSpace(value) != "" {
+			return strings.TrimSpace(value)
+		}
+	}
+	return ""
+}