Give each event its own page and show bodies the same everywhere (closes #369)

Each row of the recent events on the webhook page links to the
event's own page, /hook/{id}/events/{eventID}, and expands to show its
body; only the newest starts expanded. The event's page shows its
details, its whole body and every delivery with its attempts.

One renderer, newBodyView with templates/event_body.html, shows a body
in all three places: whole up to 32 KiB, cut there in the lists with a
link to the event's page, JSON pretty-printed, a body of more than 200
lines or 32 KiB in a scrolling box, and a body that is not text left
out beside its download link. A resubmitted copy links to its
original's page.

Model: opus-5-5

internal/server/routes.go

@@ -252,11 +252,12 @@ func (s *Server) setupSourceRoutes() {
 		r.Post("/edit", s.h.HandleSourceEditSubmit())
 		r.Post("/delete", s.h.HandleSourceDelete())
 		r.Get("/events", s.h.HandleSourceLogs())
-		// The log page renders each body only up to its cap, so
-		// this is the only route that serves a whole one. It
-		// belongs to this group for its RequireAuth and
-		// NoCache; see HandleEventBodyDownload for the headers
-		// that keep the bytes it returns inert.
+		r.Get("/events/{eventID}", s.h.HandleEventDetail())
+		// The pages show a body as escaped text and leave a
+		// binary one out, so this is the only route that serves
+		// the stored bytes. It belongs to this group for its
+		// RequireAuth and NoCache; see HandleEventBodyDownload for
+		// the headers that keep the bytes it returns inert.
 		r.Get(
 			"/events/{eventID}/body",
 			s.h.HandleEventBodyDownload(),