Move webhook pages to /hook/ID and inbound URLs to /h/UUID (closes #367)

The webhook page and everything under it move from /source/ID to
/hook/ID, the list and new-webhook form to /hooks and /hooks/new, and
the event log from .../logs to /hook/ID/events, body download
included. Entrypoint URLs move from /webhook/UUID to /h/UUID, and the
webhook page shows only that form. The old paths are gone.

Links, redirects, form actions, tests, comments and the README follow.
Both links to the event log page, and its title and heading, now read
"Full Event Log". Go identifiers and template file names are
unchanged. Route tests reach every moved page and form through the
production router, taking each URL and token from the rendered page.

Model: opus-5-5

internal/middleware/csrf.go

@@ -41,7 +41,7 @@ func (m *Middleware) CSRF() func(http.Handler) http.Handler {
 		// CSRF is registered ahead of RequireAuth on every route
 		// group that uses it, so this WARN is reachable by an
 		// unauthenticated client: a POST with no token to
-		// /source/<any length of any text>/edit lands here. The
+		// /hook/<any length of any text>/edit lands here. The
 		// method and path are capped against the same budgets as
 		// the access log. remote_addr is set by net/http from the
 		// accepted connection rather than by the client, and