fix(home): render findings flat — drop per-tool grouping

The home page was calling ``render_findings_panel``, which groups
findings by tool into expanders and renders an "Open <Tool>" page
link under each. After uploading a file, the user still saw a tool
list (just under a different shape) — defeating the earlier cleanup
that removed the tool-cards grid.

Inline a flat renderer in ``_home_page``: per uploaded file, render
the filename header + severity summary + a flat list of findings via
``_render_one_finding`` directly. No expanders, no tool names as
section headers, no per-tool page-link buttons. Tool discovery
happens in the sidebar.

``render_findings_panel`` itself is unchanged — it still groups by
tool and remains tested via the findings-panel harness, but is no
longer used on the home page.

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

src/gui/app.py

@@ -31,8 +31,13 @@ if str(_project_root) not in sys.path:
 
 def _home_page() -> None:
     """Render the home page — multi-file upload + per-file analysis."""
-    from src.gui.components import hide_streamlit_chrome, render_findings_panel
-    from src.gui.components._legacy import _run_analysis_on_upload
+    from src.gui.components import hide_streamlit_chrome
+    from src.gui.components._legacy import (
+        _render_one_finding,
+        _run_analysis_on_upload,
+        _SEVERITY_ICON,
+    )
+    from src.core.text_clean import hidden_char_css
     from src.i18n import t
 
     st.set_page_config(
@@ -121,18 +126,39 @@ def _home_page() -> None:
 
     if findings_by_file:
         st.divider()
+        # Hidden-char badge CSS is needed once for any finding-sample
+        # tables ``_render_one_finding`` may emit further down.
+        st.markdown(hidden_char_css(), unsafe_allow_html=True)
+
         # Preserve uploader order so the user sees results in the same
-        # order they appear in the file list above.
+        # order they appear in the file list above. Findings render as
+        # a flat list per file — no per-tool grouping, no "Open <Tool>"
+        # buttons. Tool discovery happens in the sidebar.
         for f in uploaded_files:
             if f.name not in findings_by_file:
                 continue
             findings = findings_by_file[f.name]
             with st.container(border=True):
-                if not findings:
                 st.markdown(f"### 📄 {f.name}")
+                if not findings:
                     st.success(t("findings.none"))
-                else:
-                    render_findings_panel(findings, header=f"📄 {f.name}")
+                    continue
+                by_sev: dict[str, int] = {}
+                for finding in findings:
+                    by_sev[finding.severity] = by_sev.get(finding.severity, 0) + 1
+                summary = " · ".join(
+                    t(
+                        "findings.severity_summary_segment",
+                        icon=_SEVERITY_ICON[s],
+                        n=by_sev[s],
+                        severity=s,
+                    )
+                    for s in ("error", "warn", "info") if by_sev.get(s)
+                )
+                if summary:
+                    st.caption(summary)
+                for finding in findings:
+                    _render_one_finding(finding)
 
     st.divider()
     st.caption(t("chrome.footer"))