fix(web): history tab copy — every chat saves automatically, there is no Save button

meta description -> locked (A3) auto-save string (history.html L6).
page-sub -> locked (A3) string, the <strong>Save</strong> emphasis retired with the button (L106-109).
empty row -> locked (A3) string; colspan=6, hidden, and row id untouched (L163).
h1, the anonymous gate section, and history.js are byte-identical — state language verified accurate.

tests/unit/test_history_page.py

@@ -216,9 +216,11 @@ def test_history_table_skeleton() -> None:
     assert "hidden" in row.group(0)
     assert 'id="history-empty-row"' in row.group(0)
     assert "<td colspan=\"6\">" in html
+    # Phase 66 (owner-locked A3, 2026-09-01): the auto-save copy —
+    # the Save button is retired (phase 55), every conversation
+    # saves itself; the old "press Save" line is gone.
     assert (
-        "No saved chats yet — finish a conversation and press"
-        " <strong>Save</strong> in the chat."
+        "No saved chats yet — start a conversation and it will be saved automatically."
     ) in html