Add embedded web chat client with C2S HTTP API

- New DB schema: users, channel_members, messages tables (migration 003)
- Full C2S HTTP API: register, channels, messages, DMs, polling
- Preact SPA embedded via embed.FS, served at GET /
- IRC-style UI: tab bar, channel messages, user list, DM tabs, /commands
- Dark theme, responsive, esbuild-bundled (~19KB)
- Polling-based message delivery (1.5s interval)
- Commands: /join, /part, /msg, /nick

internal/server/routes.go

@@ -1,9 +1,12 @@
 package server
 
 import (
+	"io/fs"
 	"net/http"
 	"time"
 
+	"git.eeqj.de/sneak/chat/web"
+
 	sentryhttp "github.com/getsentry/sentry-go/http"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
@@ -45,4 +48,47 @@ func (s *Server) SetupRoutes() {
 			r.Get("/metrics", http.HandlerFunc(promhttp.Handler().ServeHTTP))
 		})
 	}
+
+	// API v1
+	s.router.Route("/api/v1", func(r chi.Router) {
+		r.Get("/server", s.h.HandleServerInfo())
+		r.Post("/register", s.h.HandleRegister())
+		r.Get("/me", s.h.HandleMe())
+
+		// Channels
+		r.Get("/channels", s.h.HandleListChannels())
+		r.Get("/channels/all", s.h.HandleListAllChannels())
+		r.Post("/channels/join", s.h.HandleJoinChannel())
+		r.Delete("/channels/{channel}/part", s.h.HandlePartChannel())
+		r.Get("/channels/{channel}/members", s.h.HandleChannelMembers())
+		r.Get("/channels/{channel}/messages", s.h.HandleGetMessages())
+		r.Post("/channels/{channel}/messages", s.h.HandleSendMessage())
+
+		// DMs
+		r.Get("/dm/{nick}/messages", s.h.HandleGetDMs())
+		r.Post("/dm/{nick}/messages", s.h.HandleSendDM())
+
+		// Polling
+		r.Get("/poll", s.h.HandlePoll())
+	})
+
+	// Serve embedded SPA
+	distFS, err := fs.Sub(web.Dist, "dist")
+	if err != nil {
+		s.log.Error("failed to get web dist filesystem", "error", err)
+	} else {
+		fileServer := http.FileServer(http.FS(distFS))
+		s.router.Get("/*", func(w http.ResponseWriter, r *http.Request) {
+			// Try to serve the file; if not found, serve index.html for SPA routing
+			f, err := distFS.(fs.ReadFileFS).ReadFile(r.URL.Path[1:])
+			if err != nil || len(f) == 0 {
+				indexHTML, _ := distFS.(fs.ReadFileFS).ReadFile("index.html")
+				w.Header().Set("Content-Type", "text/html; charset=utf-8")
+				w.WriteHeader(http.StatusOK)
+				_, _ = w.Write(indexHTML)
+				return
+			}
+			fileServer.ServeHTTP(w, r)
+		})
+	}
 }