Make every clickable control look clickable, in two shared styles (closes #375)

Many controls were plain coloured text with no sign they could be clicked: Edit, Activate, Deactivate, Delete, Replay, Resubmit, both Add controls and the copy control beside each entrypoint URL. Every clickable control is now a real button or link in one of two shared styles: the buttons in input.css, now with a pointer cursor, and btn-small, a small bordered secondary action in style.css, which the layout now loads. The site name, the footer links and each webhook list card show at rest that they open something, with focus states. The copy control shows "Copied" after a click. Rows on the webhook page and in the event log wrap at phone width. The browser test covers the copy control.

Model: opus-5-5

internal/handlers/ui_copy_test.go

@@ -82,9 +82,9 @@ func TestNavbarUsesWebhookTerminology(t *testing.T) {
 	})
 
 	assert.Contains(t, body, "Retention: 14 days")
-	assert.Contains(t, body, `class="btn-text">Webhooks</a>`)
+	assert.Contains(t, body, `class="btn-secondary">Webhooks</a>`)
 	assert.Contains(
-		t, body, `class="btn-text w-full text-left">Webhooks</a>`,
+		t, body, `class="btn-secondary w-full">Webhooks</a>`,
 	)
 	assert.Contains(
 		t, body,
@@ -163,7 +163,7 @@ func TestEventLogPageIsCalledFullEventLog(t *testing.T) {
 	)
 	assert.Contains(
 		t, detailBody,
-		`<a href="/hook/wh-1/events" class="btn-text text-sm">Full Event Log</a>`,
+		`<a href="/hook/wh-1/events" class="btn-small">Full Event Log</a>`,
 		"the link under recent events",
 	)
 
@@ -331,8 +331,9 @@ func TestEntrypointCopyButtonIsProgressiveEnhancement(t *testing.T) {
 	assert.Contains(t, body, "https://hooks.example.com/h/abc123")
 	assert.Contains(
 		t, body,
-		`hidden data-copy-target="entrypoint-url-ep-1"`,
-		"the button must start hidden and be revealed by script",
+		`<button type="button" hidden data-copy-target="entrypoint-url-ep-1"`,
+		"the copy control must be a button, start hidden and be "+
+			"revealed by script",
 	)
 
 	// renderTemplate streams to the ResponseWriter, so an abort