feat: LLM accuracy testing framework with 17-test catalog

Framework runs a category/subcategory test catalog against multiple
LLMs through an OpenAI-compatible endpoint. Deterministic evaluators
score each response. Reports render as table, markdown, or JSON.

internal/eval/equals.go

@@ -0,0 +1,27 @@
+package eval
+
+import (
+	"context"
+	"fmt"
+	"strings"
+)
+
+// equalsEval scores full credit on a trimmed, case-insensitive exact match.
+type equalsEval struct {
+	want string
+}
+
+// Equals returns an Evaluator awarding full credit when the response,
+// trimmed and lower-cased, equals want (also trimmed and lower-cased).
+func Equals(want string) Evaluator {
+	return equalsEval{want: want}
+}
+
+func (e equalsEval) Evaluate(_ context.Context, response string) Score {
+	got := strings.ToLower(strings.TrimSpace(response))
+	want := strings.ToLower(strings.TrimSpace(e.want))
+	if got == want {
+		return Score{Value: 1, Detail: fmt.Sprintf("equals %q", e.want)}
+	}
+	return Score{Value: 0, Detail: fmt.Sprintf("got %q, want %q", strings.TrimSpace(response), e.want)}
+}