feat: implement Havenllo single-board kanban (Go+SQLite backend, Preact/Vite frontend)

- Single fixed 'Haven' board: lists (To do/In progress/Done) + cards, no multi-board
- Go 1.24 backend, CGO-free modernc.org/sqlite, embedded SPA, REST /api
- Preact + Vite + TS frontend, native HTML5 drag-and-drop, optimistic UI, dark Haven theme
- PVC (nfs-client) for SQLite, root container on NFS, simple nginx ingress havenllo.haven
- Dockerfile multi-arch build, Gitea CI via pipeline-actions@main

internal/api/handlers.go

@@ -0,0 +1,224 @@
+// Package api exposes Havenllo's same-origin JSON API and embedded SPA handler.
+package api
+
+import (
+	"io/fs"
+	"net/http"
+	"path"
+	"strings"
+
+	"havenllo/internal/app"
+)
+
+type Handler struct {
+	service *app.Service
+	static  fs.FS
+}
+
+func NewHandler(service *app.Service, static fs.FS) http.Handler {
+	h := &Handler{service: service, static: static}
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /api/health", h.health)
+	mux.HandleFunc("GET /api/board", h.board)
+	mux.HandleFunc("GET /api/lists", h.lists)
+	mux.HandleFunc("POST /api/lists", h.createList)
+	mux.HandleFunc("GET /api/lists/{id}", h.list)
+	mux.HandleFunc("PATCH /api/lists/{id}", h.updateList)
+	mux.HandleFunc("DELETE /api/lists/{id}", h.deleteList)
+	mux.HandleFunc("GET /api/lists/{id}/cards", h.cards)
+	mux.HandleFunc("POST /api/lists/{id}/cards", h.createCard)
+	mux.HandleFunc("GET /api/cards/{id}", h.card)
+	mux.HandleFunc("PATCH /api/cards/{id}", h.updateCard)
+	mux.HandleFunc("DELETE /api/cards/{id}", h.deleteCard)
+	mux.HandleFunc("/api/", h.apiNotFound)
+	mux.HandleFunc("/", h.serveApp)
+	return mux
+}
+
+func (h *Handler) health(w http.ResponseWriter, r *http.Request) {
+	if err := h.service.Health(r.Context()); err != nil {
+		writeError(w, http.StatusServiceUnavailable, "unavailable", "database is unavailable")
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+}
+
+func (h *Handler) board(w http.ResponseWriter, r *http.Request) {
+	snapshot, err := h.service.Board(r.Context())
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, snapshot)
+}
+
+func (h *Handler) lists(w http.ResponseWriter, r *http.Request) {
+	lists, err := h.service.Lists(r.Context())
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, listsResponse{Lists: listSummaries(lists)})
+}
+
+func (h *Handler) createList(w http.ResponseWriter, r *http.Request) {
+	if !requireJSON(w, r) {
+		return
+	}
+	var request createListRequest
+	if !decodeJSON(w, r, &request) {
+		return
+	}
+	list, err := h.service.CreateList(r.Context(), request.Name, request.Position)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusCreated, listResponse{List: list})
+}
+
+func (h *Handler) list(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r, "id")
+	if !ok {
+		return
+	}
+	list, err := h.service.List(r.Context(), id)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	cards, err := h.service.Cards(r.Context(), id)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, listDetailsResponse{List: list, Cards: cards})
+}
+
+func (h *Handler) updateList(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r, "id")
+	if !ok || !requireJSON(w, r) {
+		return
+	}
+	var request updateListRequest
+	if !decodeJSON(w, r, &request) {
+		return
+	}
+	list, err := h.service.UpdateList(r.Context(), id, request.Name, request.Position)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, listResponse{List: list})
+}
+
+func (h *Handler) deleteList(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r, "id")
+	if !ok {
+		return
+	}
+	if err := h.service.DeleteList(r.Context(), id); err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (h *Handler) cards(w http.ResponseWriter, r *http.Request) {
+	listID, ok := pathID(w, r, "id")
+	if !ok {
+		return
+	}
+	cards, err := h.service.Cards(r.Context(), listID)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, cardsResponse{Cards: cards})
+}
+
+func (h *Handler) createCard(w http.ResponseWriter, r *http.Request) {
+	listID, ok := pathID(w, r, "id")
+	if !ok || !requireJSON(w, r) {
+		return
+	}
+	var request createCardRequest
+	if !decodeJSON(w, r, &request) {
+		return
+	}
+	card, err := h.service.CreateCard(r.Context(), listID, request.Title, request.Description, request.Position)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusCreated, cardResponse{Card: card})
+}
+
+func (h *Handler) card(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r, "id")
+	if !ok {
+		return
+	}
+	card, err := h.service.Card(r.Context(), id)
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, cardResponse{Card: card})
+}
+
+func (h *Handler) updateCard(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r, "id")
+	if !ok || !requireJSON(w, r) {
+		return
+	}
+	var request updateCardRequest
+	if !decodeJSON(w, r, &request) {
+		return
+	}
+	card, err := h.service.UpdateCard(r.Context(), id, app.CardPatch{
+		Title: request.Title, Description: request.Description, Done: request.Done, ListID: request.ListID, Position: request.Position,
+	})
+	if err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, cardResponse{Card: card})
+}
+
+func (h *Handler) deleteCard(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r, "id")
+	if !ok {
+		return
+	}
+	if err := h.service.DeleteCard(r.Context(), id); err != nil {
+		writeDomainError(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (h *Handler) apiNotFound(w http.ResponseWriter, r *http.Request) {
+	writeError(w, http.StatusNotFound, "not_found", "API endpoint not found")
+}
+
+func (h *Handler) serveApp(w http.ResponseWriter, r *http.Request) {
+	if h.static == nil {
+		writeError(w, http.StatusNotFound, "not_found", "application bundle not found")
+		return
+	}
+	requested := strings.TrimPrefix(path.Clean(r.URL.Path), "/")
+	if requested != "" {
+		if _, err := fs.Stat(h.static, requested); err == nil {
+			http.FileServer(http.FS(h.static)).ServeHTTP(w, r)
+			return
+		}
+	}
+	index, err := fs.ReadFile(h.static, "index.html")
+	if err != nil {
+		writeError(w, http.StatusNotFound, "not_found", "application bundle not found")
+		return
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	_, _ = w.Write(index)
+}