spec: add qq-basic specification

plots/qq-basic/specification.md

@@ -0,0 +1,25 @@
+# qq-basic: Basic Q-Q Plot
+
+## Description
+
+A Q-Q (Quantile-Quantile) plot compares the distribution of a dataset against a theoretical distribution (typically normal) or another dataset. Points are plotted by matching sample quantiles to theoretical quantiles, with a diagonal reference line indicating perfect distribution match. Deviations from the line reveal distribution characteristics such as skewness, heavy tails, and outliers.
+
+## Applications
+
+- Testing normality assumptions before parametric statistical tests (t-tests, ANOVA, regression)
+- Identifying distribution characteristics such as skewness and kurtosis in research datasets
+- Quality control analysis to verify process measurements follow expected distributions
+- Detecting outliers and data quality issues in experimental data
+
+## Data
+
+- `sample` (numeric) - The observed data values to compare against the reference distribution
+- Reference: Normal distribution (default) with parameters estimated from sample
+- Size: 30-500 observations recommended for meaningful visual comparison
+
+## Notes
+
+- Points falling along the diagonal reference line indicate data follows the reference distribution
+- Systematic deviations reveal specific distribution characteristics: S-curves indicate skewness, curved ends indicate heavy or light tails
+- The 45-degree reference line (y=x) should be clearly visible
+- Axis labels should indicate "Theoretical Quantiles" and "Sample Quantiles"

plots/qq-basic/specification.yaml

@@ -0,0 +1,30 @@
+# Specification-level metadata for qq-basic
+# Auto-synced to PostgreSQL on push to main
+
+spec_id: qq-basic
+title: Basic Q-Q Plot
+
+# Specification tracking
+created: 2025-12-15T20:41:58Z
+issue: 977
+suggested: MarkusNeusinger
+history: []
+
+# Classification tags (applies to all library implementations)
+tags:
+  plot_type:
+    - qq
+    - diagnostic
+  domain:
+    - statistics
+    - science
+    - quality-control
+  features:
+    - basic
+    - distribution
+    - normality
+  audience:
+    - intermediate
+  data_type:
+    - numeric
+    - continuous