feat(client): ConsideringPhrases — authored rotating think-lines (§13)

client/content/considering.json

@@ -0,0 +1,9 @@
+{
+  "considering": [
+    "The Master considers your words.",
+    "Somewhere, dice are gathered.",
+    "The tale weighs its next turn.",
+    "The dark shifts, thinking.",
+    "A page is turned, unhurried."
+  ]
+}