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

Each event now has its own page at /hook/ID/events/EVENTID, behind the login, showing its details, its whole body and every delivery; a resubmitted copy links to its original's page. The recent events on the webhook page link there and expand to show their bodies, only the newest expanded on load. One renderer and one template show a body the same way in the recent events, the event log and the event's page: whole up to 32 KiB, cut there in the two lists with links to the event's page and the download; JSON pretty-printed unless that would grow it past four times plus 1 KiB; over 200 lines in a scrolling box; a body holding NUL or control characters treated as binary and never dumped raw.

Model: opus-5-5

internal/handlers/handlers.go

@@ -150,16 +150,23 @@ func New(
 
 	// Parse all page templates once at startup
 	s.templates = map[string]*template.Template{
-		"login.html":         parsePageTemplate("login.html"),
-		"profile.html":       parsePageTemplate("profile.html"),
-		"settings.html":      parsePageTemplate("settings.html"),
-		"sources_list.html":  parsePageTemplate("sources_list.html"),
-		"sources_new.html":   parsePageTemplate("sources_new.html"),
-		"source_detail.html": parsePageTemplate("source_detail.html", "webhook_stats.html"),
-		"source_edit.html":   parsePageTemplate("source_edit.html"),
-		"source_logs.html":   parsePageTemplate("source_logs.html"),
-		"target_edit.html":   parsePageTemplate("target_edit.html"),
-		"error.html":         parsePageTemplate("error.html"),
+		"login.html":        parsePageTemplate("login.html"),
+		"profile.html":      parsePageTemplate("profile.html"),
+		"settings.html":     parsePageTemplate("settings.html"),
+		"sources_list.html": parsePageTemplate("sources_list.html"),
+		"sources_new.html":  parsePageTemplate("sources_new.html"),
+		"source_detail.html": parsePageTemplate(
+			"source_detail.html", "webhook_stats.html", "event_body.html",
+		),
+		"source_edit.html": parsePageTemplate("source_edit.html"),
+		"source_logs.html": parsePageTemplate(
+			"source_logs.html", "event_body.html", "delivery_attempts.html",
+		),
+		"event_detail.html": parsePageTemplate(
+			"event_detail.html", "event_body.html", "delivery_attempts.html",
+		),
+		"target_edit.html": parsePageTemplate("target_edit.html"),
+		"error.html":       parsePageTemplate("error.html"),
 	}
 
 	lc.Append(fx.Hook{
@@ -386,7 +393,7 @@ func (s *Handlers) pageData(
 // partial body and the status before a mid-render error can be
 // reported, leaving no way to serve a 500. Buffering makes a page's
 // rendered size resident memory per concurrent viewer, so every page
-// owes it a bound: the event log caps each stored body at
+// owes it a bound: the lists of events cap each stored body at
 // maxRenderedBodyBytes for exactly this reason.
 func (s *Handlers) executeTemplate(
 	w http.ResponseWriter,