Render delivery attempt detail in the event log (closes #202) (#219)

delivery_results stored status_code, response_body, error, duration and
attempt_num, and no template rendered any of it, so a failure read as
"target: failed" and diagnosing it meant opening the per-webhook SQLite
file by hand.

An expanded delivery now lists its attempts with attempt number, status
code, duration, error and response body. The body is bounded in the query
rather than read whole and truncated in Go (#135), and a body the engine
itself cut is no longer presented as complete.

The response body and error are untrusted remote content, so target
credentials are removed before rendering. Two cases needed care: a secret
severed by the 4096-byte cut matches nothing as a whole string, and the
engine's io.LimitReader cuts at the same constant the renderer uses, so
the guard keys on the body reaching the cap rather than on the stored size
exceeding it. Empty secrets are filtered where the secret list is built,
because an empty string passed to strings.ReplaceAll inserts the marker at
every byte boundary.

loadTargetMap builds the redactor half unscoped, so a soft-deleted
target's historical deliveries still render redacted.

Also regenerates static/css/tailwind.css, which had drifted from the
templates: hover:text-red-700, text-red-500, underline and w-28 were in
use but absent from the served stylesheet (#236).

internal/delivery/export_test.go

@@ -25,6 +25,12 @@ const (
 	ExportRetryChannelSize        = retryChannelSize
 	ExportDefaultFailureThreshold = defaultFailureThreshold
 	ExportDefaultCooldown         = defaultCooldown
+
+	// ExportMaxBodyLog is the cap the engine applies to a
+	// recorded response body. The event log's handling of a cut
+	// response is written against this number, so a test has to
+	// be able to name it.
+	ExportMaxBodyLog = maxBodyLog
 )
 
 // ExportIsBlockedIP exposes isBlockedIP for testing.