feat: add subtext_card component for between_the_lines display

Adds _SIGNAL_TYPE_LABELS (FR labels + indigo/red/amber/gray/sky palette)
and subtext_card(item) rendering observation → reading → implication with
signal-type chip, AI badge, collapsible evidence quote, and meta row.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dashboard/components.py

@@ -575,3 +575,95 @@ def delta_card(delta: dict) -> None:
         f'</div>',
         unsafe_allow_html=True,
     )
+
+
+# ── Between-the-lines / SubtextRead card ─────────────────────────────────────
+
+_SIGNAL_TYPE_LABELS: dict[str, tuple[str, str, str]] = {
+    # signal_type → (label_fr, fg_color, bg_color)
+    "language_drift":     ("Dérive de langage",      "#4f46e5", "#eef2ff"),  # indigo
+    "qa_evasion":         ("Évasion en Q&A",          "#dc2626", "#fef2f2"),  # red
+    "omission":           ("Omission",                "#d97706", "#fffbeb"),  # amber
+    "emphasis_shift":     ("Déplacement d'emphase",   "#6b7280", "#f3f4f6"),  # gray
+    "accounting_quality": ("Qualité comptable",       "#0ea5e9", "#f0f9ff"),  # sky
+}
+
+
+def subtext_card(item: dict) -> None:
+    """Render a SubtextRead observation as a structured card in Streamlit.
+
+    Displays: signal-type chip + AI badge, observation, expert reading,
+    implication (à surveiller), and collapsible evidence quote with meta row.
+    """
+    observation = item.get("observation", "")
+    reading = item.get("reading", "")
+    signal_type = item.get("signal_type", "")
+    implication = item.get("implication", "")
+    evidence = item.get("evidence") or {}
+
+    # Resolve signal type styling; fall back to AMBER/WARN_BG for unknowns
+    if signal_type in _SIGNAL_TYPE_LABELS:
+        sig_label, fg_color, sig_bg = _SIGNAL_TYPE_LABELS[signal_type]
+    else:
+        sig_label, fg_color, sig_bg = "Signal", AMBER, WARN_BG
+
+    # Signal type chip — pill style matching tension_card's weight_chip
+    signal_chip = (
+        f'<span style="background:{sig_bg};color:{fg_color};border:1px solid {fg_color}33;'
+        f'border-radius:4px;padding:1px 7px;font-size:0.65rem;font-weight:600;'
+        f'text-transform:uppercase;letter-spacing:0.06em;">{sig_label}</span>'
+    )
+
+    # Evidence fields
+    ev_snippet = evidence.get("evidence_snippet", "") if isinstance(evidence, dict) else ""
+    ev_rel     = evidence.get("reliability", "")      if isinstance(evidence, dict) else ""
+    ev_src     = evidence.get("source", "")            if isinstance(evidence, dict) else ""
+    ev_imp     = (evidence.get("impact", "") or "")   if isinstance(evidence, dict) else ""
+
+    st.markdown(
+        f'<div class="primer-card" style="background:{BG};border:1px solid {BORDER};'
+        f'border-left:4px solid {fg_color};border-radius:10px;'
+        f'padding:16px 18px;margin-bottom:10px;">'
+
+        # ── Top row: chip left, AI badge right ────────────────────────────
+        f'<div style="display:flex;align-items:center;justify-content:space-between;'
+        f'margin-bottom:12px;">'
+        f'{signal_chip}'
+        f'{ai_badge("entre les lignes")}'
+        f'</div>'
+
+        # ── OBSERVATION ────────────────────────────────────────────────────
+        f'<div style="margin-bottom:10px;">'
+        f'{eyebrow_label("Observation", TEXT_MUTED)}'
+        f'<div style="font-size:{FS_BODY};color:{TEXT};line-height:1.55;margin-top:4px;">'
+        f'{observation}'
+        f'</div>'
+        f'</div>'
+
+        # ── LECTURE EXPERTE ────────────────────────────────────────────────
+        f'<div style="margin-bottom:12px;">'
+        f'{eyebrow_label("Lecture experte", fg_color)}'
+        f'<div style="font-size:{FS_BODY};font-style:italic;color:{TEXT};'
+        f'line-height:1.55;margin-top:4px;">'
+        f'{reading}'
+        f'</div>'
+        f'</div>'
+
+        # ── Separator ──────────────────────────────────────────────────────
+        f'<div style="border-top:1px solid {BORDER};margin-bottom:12px;"></div>'
+
+        # ── À SURVEILLER ──────────────────────────────────────────────────
+        f'<div style="margin-bottom:10px;">'
+        f'{eyebrow_label("À surveiller", AMBER)}'
+        f'<div style="font-size:{FS_BODY};color:{TEXT_MUTED};line-height:1.55;margin-top:4px;">'
+        f'{implication}'
+        f'</div>'
+        f'</div>'
+
+        # ── Evidence quote + meta row ──────────────────────────────────────
+        f'{evidence_quote(ev_snippet, bg=BG_MUTED, border_color=BORDER)}'
+        f'{meta_row(ev_rel, ev_src, ev_imp)}'
+
+        f'</div>',
+        unsafe_allow_html=True,
+    )