feat: add minimal web dashboard with stats, top credentials, and sessions

Implements Phase 1.5 — an embedded web UI using Go templates, Pico CSS
(dark theme), and htmx for auto-refreshing stats and active sessions.

Adds read query methods to the Store interface (GetDashboardStats,
GetTopUsernames, GetTopPasswords, GetTopIPs, GetRecentSessions) with
implementations for both SQLite and MemoryStore. Introduces the
internal/web package with server, handlers, templates, and tests.
Web server is opt-in via [web] config section and runs alongside
SSH with graceful shutdown. Bumps version to 0.2.0.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/web/handlers.go

@@ -0,0 +1,104 @@
+package web
+
+import (
+	"net/http"
+
+	"git.t-juice.club/torjus/oubliette/internal/storage"
+)
+
+type dashboardData struct {
+	Stats          *storage.DashboardStats
+	TopUsernames   []storage.TopEntry
+	TopPasswords   []storage.TopEntry
+	TopIPs         []storage.TopEntry
+	ActiveSessions []storage.Session
+	RecentSessions []storage.Session
+}
+
+func (s *Server) handleDashboard(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	stats, err := s.store.GetDashboardStats(ctx)
+	if err != nil {
+		s.logger.Error("failed to get dashboard stats", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	topUsernames, err := s.store.GetTopUsernames(ctx, 10)
+	if err != nil {
+		s.logger.Error("failed to get top usernames", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	topPasswords, err := s.store.GetTopPasswords(ctx, 10)
+	if err != nil {
+		s.logger.Error("failed to get top passwords", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	topIPs, err := s.store.GetTopIPs(ctx, 10)
+	if err != nil {
+		s.logger.Error("failed to get top IPs", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	activeSessions, err := s.store.GetRecentSessions(ctx, 50, true)
+	if err != nil {
+		s.logger.Error("failed to get active sessions", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	recentSessions, err := s.store.GetRecentSessions(ctx, 50, false)
+	if err != nil {
+		s.logger.Error("failed to get recent sessions", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	data := dashboardData{
+		Stats:          stats,
+		TopUsernames:   topUsernames,
+		TopPasswords:   topPasswords,
+		TopIPs:         topIPs,
+		ActiveSessions: activeSessions,
+		RecentSessions: recentSessions,
+	}
+
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if err := s.tmpl.ExecuteTemplate(w, "layout.html", data); err != nil {
+		s.logger.Error("failed to render dashboard", "err", err)
+	}
+}
+
+func (s *Server) handleFragmentStats(w http.ResponseWriter, r *http.Request) {
+	stats, err := s.store.GetDashboardStats(r.Context())
+	if err != nil {
+		s.logger.Error("failed to get dashboard stats", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if err := s.tmpl.ExecuteTemplate(w, "stats", stats); err != nil {
+		s.logger.Error("failed to render stats fragment", "err", err)
+	}
+}
+
+func (s *Server) handleFragmentActiveSessions(w http.ResponseWriter, r *http.Request) {
+	sessions, err := s.store.GetRecentSessions(r.Context(), 50, true)
+	if err != nil {
+		s.logger.Error("failed to get active sessions", "err", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if err := s.tmpl.ExecuteTemplate(w, "active_sessions", sessions); err != nil {
+		s.logger.Error("failed to render active sessions fragment", "err", err)
+	}
+}