test: cover help_md keys, header smoke, and bilingual ES smoke

Two stale Spanish smoke assertions still expected English page titles
for PDF Extractor and Reconciler — the i18n work landed real
translations ("PDF a CSV", "Reconciliar dos archivos"), so refresh the
expected substrings and the surrounding comment.

Add new coverage for the help-popover feature:
- TestHelpPopoverKeys (test_lang_packs): every tool_id resolves a
  non-empty tools.<id>.help_md in BOTH packs; help.button_label and
  help.missing_body resolve in both.
- TestDescriptionCopy (test_tools_registry): every Tool.description
  non-empty and under 120 chars — pins the post-jargon-scrub copy
  so future drift back into multi-clause prose is loud.
- TestRenderToolHeaderSmoke: render_tool_header is callable, listed
  in components.__all__, and every i18n key it touches resolves in
  both packs. Runs without a Streamlit script context.

Suite: 2427 passed (+9 new), 91 skipped.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/gui/test_smoke.py

@@ -63,12 +63,11 @@ EXPECTED_SUBSTRINGS: dict[str, dict[str, str]] = {
     "7_Multi_File_Merger":   {"en": "Combine Files",     "es": "Combinar archivos"},
     "8_Validator_Reporter":  {"en": "Quality Check",     "es": "Verificación de calidad"},
     "9_Pipeline_Runner":     {"en": "Automated",         "es": "Flujos automatizados"},
-    # The PDF Extractor and Reconciler pages are English-only today
-    # (translations tracked as a follow-up). The smoke test value is
-    # still that the page *renders at all* in 'es'; the substring is
-    # the same English hero text under both languages.
-    "10_PDF_Extractor":      {"en": "PDF to CSV",        "es": "PDF to CSV"},
-    "11_Reconciler":         {"en": "Reconcile",         "es": "Reconcile"},
+    # PDF Extractor + Reconciler page titles are now translated in
+    # both packs (``tools.<id>.page_title``). Their hero copy diverges
+    # by language, so the smoke test pins the localized substring.
+    "10_PDF_Extractor":      {"en": "PDF to CSV",        "es": "PDF a CSV"},
+    "11_Reconciler":         {"en": "Reconcile",         "es": "Reconciliar"},
     "99_Close":              {"en": "Shutting down",     "es": "Cerrando"},
 }