feat(plotly): implement bullet-basic (#1039)

## Implementation: `bullet-basic` - plotly

Implements the **plotly** version of `bullet-basic`.

**File:** `plots/bullet-basic/implementations/plotly.py`

**Parent Issue:** #999

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20257947593)*

---------

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/bullet-basic/implementations/plotly.py

@@ -0,0 +1,112 @@
+"""
+bullet-basic: Basic Bullet Chart
+Library: plotly
+"""
+
+import plotly.graph_objects as go
+from plotly.subplots import make_subplots
+
+
+# Data - Multiple KPIs with different performance levels
+metrics = [
+    {"label": "Revenue ($K)", "actual": 275, "target": 250, "ranges": [150, 200, 300]},
+    {"label": "Profit ($K)", "actual": 85, "target": 100, "ranges": [50, 75, 125]},
+    {"label": "Customers", "actual": 320, "target": 400, "ranges": [200, 350, 500]},
+    {"label": "Satisfaction", "actual": 4.2, "target": 4.5, "ranges": [3.0, 4.0, 5.0]},
+]
+
+# Grayscale colors for qualitative ranges (poor -> satisfactory -> good)
+range_colors = ["#D9D9D9", "#BFBFBF", "#A6A6A6"]
+
+# Create subplots - one row per metric for proper scaling
+fig = make_subplots(
+    rows=len(metrics), cols=1, shared_xaxes=False, vertical_spacing=0.12, subplot_titles=[m["label"] for m in metrics]
+)
+
+# Create each bullet chart in its own subplot
+for i, m in enumerate(metrics):
+    row = i + 1
+
+    # Add qualitative range bands (background, plotted in reverse order)
+    for j, r in enumerate(reversed(m["ranges"])):
+        fig.add_trace(
+            go.Bar(
+                x=[r],
+                y=[""],
+                orientation="h",
+                marker=dict(color=range_colors[len(m["ranges"]) - 1 - j]),
+                width=0.6,
+                showlegend=False,
+                hoverinfo="skip",
+            ),
+            row=row,
+            col=1,
+        )
+
+    # Add actual value bar (primary measure)
+    fig.add_trace(
+        go.Bar(
+            x=[m["actual"]],
+            y=[""],
+            orientation="h",
+            marker=dict(color="#306998"),
+            width=0.25,
+            showlegend=False,
+            name=m["label"],
+            hovertemplate=f"{m['label']}: {m['actual']}<extra></extra>",
+        ),
+        row=row,
+        col=1,
+    )
+
+    # Add target marker line
+    fig.add_shape(
+        type="line",
+        x0=m["target"],
+        x1=m["target"],
+        y0=-0.4,
+        y1=0.4,
+        line=dict(color="#1A1A1A", width=5),
+        row=row,
+        col=1,
+    )
+
+    # Add actual value annotation
+    max_range = m["ranges"][-1]
+    fig.add_annotation(
+        x=max_range * 1.02,
+        y=0,
+        text=f"<b>{m['actual']}</b>",
+        showarrow=False,
+        font=dict(size=20, color="#306998"),
+        xanchor="left",
+        row=row,
+        col=1,
+    )
+
+    # Update x-axis range for each subplot
+    fig.update_xaxes(
+        range=[0, max_range * 1.15], tickfont=dict(size=16), showgrid=True, gridcolor="rgba(0,0,0,0.1)", row=row, col=1
+    )
+
+    fig.update_yaxes(showticklabels=False, row=row, col=1)
+
+# Layout
+fig.update_layout(
+    title=dict(text="bullet-basic · plotly · pyplots.ai", font=dict(size=32), x=0.5, xanchor="center"),
+    barmode="overlay",
+    template="plotly_white",
+    margin=dict(l=80, r=100, t=120, b=60),
+    showlegend=False,
+    height=900,
+    width=1600,
+)
+
+# Update subplot titles font size
+for annotation in fig["layout"]["annotations"]:
+    if "text" in annotation and annotation["text"] in [m["label"] for m in metrics]:
+        annotation["font"] = dict(size=22)
+
+# Save
+fig.write_image("plot.png", width=1600, height=900, scale=3)
+fig.write_html("plot.html", include_plotlyjs="cdn")

plots/bullet-basic/metadata/plotly.yaml

@@ -0,0 +1,23 @@
+# Per-library metadata for plotly implementation of bullet-basic
+# Auto-generated by impl-generate.yml
+
+library: plotly
+specification_id: bullet-basic
+
+# Preview URLs (filled by workflow)
+preview_url: https://storage.googleapis.com/pyplots-images/plots/bullet-basic/plotly/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/bullet-basic/plotly/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/bullet-basic/plotly/plot.html
+
+current:
+  version: 0
+  generated_at: 2025-12-16T05:52:30Z
+  generated_by: claude-opus-4-5-20251101
+  workflow_run: 20257947593
+  issue: 999
+  quality_score: 93
+  # Version info (filled by workflow)
+  python_version: "3.13.11"
+  library_version: "unknown"
+
+history: []