refactor(gui): drop Review page + normalization gate

Home is now the only entry point: the "Run analysis" button on the
upload section IS the review step (findings render inline via
render_findings_panel). Tool pages no longer gate on a passed
normalization — running the analyzer is sufficient context.

Removed:
- src/gui/pages/0_Review.py
- src/gui/components/gate.py (re-export seam)
- require_normalization_gate() in src/gui/components/_legacy.py
- "review" section enum in tools_registry.py
- Data Review entry in app.py navigation
- require_normalization_gate() calls + imports in all nine tool pages
- tests/gui/test_gate.py (whole file)
- TestReviewWorkflow in tests/gui/test_workflows.py
- 0_Review entry in tests/gui/test_smoke.py PAGE_SLUGS
- stash_upload's normalization_result+normalization_for stashing
- stash_upload_without_gate (was the gate's negative-path helper)

2017 tests pass (16 retired with the gate flow).

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

src/gui/components/_legacy.py

@@ -1264,45 +1264,6 @@ class _StashedUpload:
         return self._data
 
 
-def require_normalization_gate() -> None:
-    """Block the calling tool page until the upload has passed the gate.
-
-    Tool pages should call this immediately after their imports. When the
-    current session upload has not been normalized — no
-    ``normalization_result``, the result is for a different upload, or the
-    result didn't pass — the user is shown a banner and a button to jump
-    to the Review page; the rest of the page is short-circuited via
-    ``st.stop()``.
-
-    Pages that genuinely don't need a clean dataframe (rare) can opt out
-    by simply not calling this.
-    """
-    import hashlib
-    has_upload = st.session_state.get("home_uploaded_bytes") is not None
-    if not has_upload:
-        # No upload yet — let the page's own uploader handle it; the gate
-        # will kick in once a file is present.
-        return
-
-    upload_hash = hashlib.sha256(
-        st.session_state["home_uploaded_bytes"]
-    ).hexdigest()
-    result = st.session_state.get("normalization_result")
-    matched = (
-        result is not None
-        and st.session_state.get("normalization_for") == upload_hash
-        and getattr(result, "passed", False)
-    )
-    if matched:
-        return
-
-    name = st.session_state.get("home_uploaded_name") or _t("gate.default_name")
-    st.warning(_t("gate.warning", name=name))
-    if st.button(_t("gate.open_review"), type="primary"):
-        st.switch_page("pages/0_Review.py")
-    st.stop()
-
-
 def pickup_or_upload(
     *,
     label: str,