spec: add treemap-basic specification

plots/treemap-basic/specification.md

@@ -0,0 +1,26 @@
+# treemap-basic: Basic Treemap
+
+## Description
+
+A treemap displaying hierarchical data as nested rectangles, where each rectangle's area is proportional to its value. This visualization excels at showing part-to-whole relationships in hierarchical structures, making it easy to spot large and small items at a glance. Treemaps efficiently use screen space to display large amounts of hierarchical data in a compact form.
+
+## Applications
+
+- Disk space usage visualization by folder and file size
+- Budget allocation breakdown by department and project
+- Market capitalization comparison by sector and company
+- Website traffic analysis by country and city
+
+## Data
+
+- `category` (string) - main category or parent group
+- `subcategory` (string) - optional sub-category for nested hierarchy
+- `value` (numeric) - size/magnitude determining each rectangle's area
+- Size: 5-50 items
+
+## Notes
+
+- Use distinct colors for main categories to aid quick identification
+- Add labels for larger rectangles; smaller ones may omit labels for clarity
+- Include subtle borders between rectangles to show hierarchy boundaries
+- Show hierarchy through nesting depth or color shading intensity

plots/treemap-basic/specification.yaml

@@ -0,0 +1,31 @@
+# Specification-level metadata for treemap-basic
+# Auto-synced to PostgreSQL on push to main
+
+spec_id: treemap-basic
+title: Basic Treemap
+
+# Specification tracking
+created: 2025-12-14T11:15:11Z
+issue: 766
+suggested: MarkusNeusinger
+history: []
+
+# Classification tags (applies to all library implementations)
+tags:
+  plot_type:
+    - treemap
+    - hierarchical
+  domain:
+    - general
+    - business
+    - finance
+  features:
+    - basic
+    - hierarchical
+    - part-to-whole
+  audience:
+    - beginner
+    - intermediate
+  data_type:
+    - categorical
+    - numeric