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 from /sources to /hooks and /hooks/new; the event log from .../logs to /hook/ID/events; entrypoint URLs, the ones senders post to, from /webhook/UUID to /h/UUID. The old paths are simply gone, per the owner's ruling. Every link, redirect, form action, test, comment and README mention follows; every link to the event log, and its title and heading, read "Full Event Log".

Keeping the UUID out of logs, metrics labels and error reports, and the receiver rate limits, key on the route itself, so they cover /h/ unchanged. Routed tests follow every link and form the pages render to a moved page.

Model: opus-5-5

internal/middleware/ratelimit.go

@@ -63,7 +63,7 @@ const (
 
 	// receiverAggregateMultiplier scales the configured
 	// per-entrypoint receiver limit into the aggregate limit one
-	// client IP may spend across the whole /webhook/* route. Ten
+	// client IP may spend across the whole /h/* route. Ten
 	// entrypoints' worth lets a single sender address drive several
 	// entrypoints at their full rate, while still capping what one
 	// address costs the unauthenticated receiver.
@@ -389,7 +389,7 @@ func (m *Middleware) postRateLimit(
 // It is Config.ReceiverRateLimit requests per minute.
 //
 // That limit alone bounds nothing in aggregate. The route pattern
-// /webhook/{uuid} matches any single segment, so a client that
+// /h/{uuid} matches any single segment, so a client that
 // invents a fresh path per request mints a fresh bucket per request
 // and never refills one — and every such request still reaches the
 // handler's entrypoint lookup before it 404s. The outer limit is