feat: add local repository type with repo_type field

Introduces repo_type (remote/local) as a separate axis from package_type
so that any package type can be hosted locally. A terraform local repo
is package_type=terraform + repo_type=local.

- Remote model gains RepoType field (defaults to "remote")
- Database schema adds repo_type column with migration for existing DBs
- V1 proxy adds /api/v1/local/{name}/* route for serving local files
- V2 upload via PUT /api/v2/remotes/{name}/files/{path} checks
  repo_type=local and returns 409 on duplicate (no overwrites)
- V2 create validates repo_type and requires base_url only for remotes
- Removes the previous terraform-local PackageType approach

internal/api/v2/local.go

@@ -0,0 +1,143 @@
+package v2
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/storage"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+type LocalHandler struct {
+	db    *database.DB
+	store *storage.S3
+	cas   *storage.CAS
+}
+
+func NewLocalHandler(db *database.DB, store *storage.S3) *LocalHandler {
+	return &LocalHandler{
+		db:    db,
+		store: store,
+		cas:   storage.NewCAS(store),
+	}
+}
+
+func (h *LocalHandler) Routes() chi.Router {
+	r := chi.NewRouter()
+	r.Put("/*", h.upload)
+	r.Get("/*", h.download)
+	r.Delete("/*", h.remove)
+	return r
+}
+
+func (h *LocalHandler) upload(w http.ResponseWriter, r *http.Request) {
+	repoName := chi.URLParam(r, "name")
+	filePath := chi.URLParam(r, "*")
+
+	if filePath == "" {
+		http.Error(w, "file path required", http.StatusBadRequest)
+		return
+	}
+
+	remote, err := h.db.GetRemote(r.Context(), repoName)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("remote %q not found", repoName), http.StatusNotFound)
+		return
+	}
+	if remote.RepoType != models.RepoTypeLocal {
+		http.Error(w, "upload only allowed for local repository types", http.StatusBadRequest)
+		return
+	}
+
+	existing, err := h.db.GetLocalFile(r.Context(), repoName, filePath)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if existing != nil {
+		http.Error(w, fmt.Sprintf("file %q already exists; overwrites are not allowed", filePath), http.StatusConflict)
+		return
+	}
+
+	prov, err := provider.Get(remote.PackageType)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	contentType := prov.ContentType(filePath)
+	if ct := r.Header.Get("Content-Type"); ct != "" && ct != "application/octet-stream" {
+		contentType = ct
+	}
+
+	result, err := h.cas.Store(r.Context(), r.Body, contentType)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("store failed: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	if err := h.db.UpsertBlob(r.Context(), result.ContentHash, result.S3Key, result.SizeBytes, contentType); err != nil {
+		http.Error(w, fmt.Sprintf("record blob: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	if err := h.db.CreateLocalFile(r.Context(), repoName, filePath, result.ContentHash); err != nil {
+		if errors.Is(err, database.ErrAlreadyExists) {
+			http.Error(w, fmt.Sprintf("file %q already exists; overwrites are not allowed", filePath), http.StatusConflict)
+			return
+		}
+		http.Error(w, fmt.Sprintf("record file: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, map[string]any{
+		"path":         filePath,
+		"content_hash": result.ContentHash,
+		"size_bytes":   result.SizeBytes,
+	})
+}
+
+func (h *LocalHandler) download(w http.ResponseWriter, r *http.Request) {
+	repoName := chi.URLParam(r, "name")
+	filePath := chi.URLParam(r, "*")
+
+	file, err := h.db.GetLocalFile(r.Context(), repoName, filePath)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if file == nil {
+		http.Error(w, "not found", http.StatusNotFound)
+		return
+	}
+
+	s3Key := storage.BlobKey(file.ContentHash[len("sha256:"):])
+	reader, info, err := h.store.Download(r.Context(), s3Key)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("download failed: %v", err), http.StatusInternalServerError)
+		return
+	}
+	defer reader.Close()
+
+	w.Header().Set("Content-Type", info.ContentType)
+	w.Header().Set("Content-Length", fmt.Sprintf("%d", info.Size))
+	w.WriteHeader(http.StatusOK)
+	io.Copy(w, reader)
+}
+
+func (h *LocalHandler) remove(w http.ResponseWriter, r *http.Request) {
+	repoName := chi.URLParam(r, "name")
+	filePath := chi.URLParam(r, "*")
+
+	if err := h.db.DeleteLocalFile(r.Context(), repoName, filePath); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}