Add Phase 2+3 features: antonyms, backing, pronunciation, etymology, difficulty, affix expansion

New endpoints: /antonyms, /backing, /pronunciation, /etymology with difficulty
scoring on /random. Cross-language synset backing links French/Portuguese words
to English equivalents via WordNet 3.0 synset IDs (matching WOLF and OMW offsets).

New loaders: Hunspell affix expansion (fr, pt-PT), English programmatic inflector,
CMU Pronouncing Dictionary, SUBTLEX-US frequency, CETEMPúblico frequency,
Open Multilingual Wordnet (Portuguese), and SQL-based difficulty scoring.

Schema v2 adds tables: antonyms, synsets, word_synsets, pronunciations, etymology
with migration support for existing databases.

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

cmd/server/bench_test.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"dreamdict/internal/dictionary"
+
+	_ "modernc.org/sqlite"
+)
+
+func setupBenchServer(b *testing.B) *http.ServeMux {
+	b.Helper()
+	db, err := sql.Open("sqlite", ":memory:?_pragma=foreign_keys(on)")
+	if err != nil {
+		b.Fatal(err)
+	}
+	db.SetMaxOpenConns(1)
+	if err := dictionary.BootstrapSchema(db); err != nil {
+		b.Fatal(err)
+	}
+
+	exec := func(q string, args ...any) {
+		if _, err := db.Exec(q, args...); err != nil {
+			b.Fatalf("seed: %s: %v", q, err)
+		}
+	}
+
+	exec("INSERT INTO meta (key, value) VALUES ('schema_version', '1')")
+	exec("INSERT INTO meta (key, value) VALUES ('imported_at', '2025-01-01T00:00:00Z')")
+
+	poses := []string{"noun", "verb", "adjective", "adverb"}
+	for i := 1; i <= 500; i++ {
+		pos := poses[i%len(poses)]
+		word := fmt.Sprintf("word%04d", i)
+		exec("INSERT INTO words (id, word, lang, pos, frequency) VALUES (?, ?, 'en', ?, ?)",
+			i, word, pos, i%100)
+		exec("INSERT INTO definitions (word_id, pos, gloss, source, priority) VALUES (?, ?, ?, 'wordnet', 10)",
+			i, pos, fmt.Sprintf("def of %s", word))
+		exec("INSERT INTO synonyms (word_id, synonym, source) VALUES (?, ?, 'wordnet')",
+			i, fmt.Sprintf("syn_%s", word))
+		exec("INSERT INTO translations (word_id, translation, target_lang, source) VALUES (?, ?, 'fr', 'wiktionary')",
+			i, fmt.Sprintf("fr_%s", word))
+	}
+
+	dict := dictionary.NewFromDB(db)
+	b.Cleanup(func() { db.Close() })
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /valid", handleValid(dict))
+	mux.HandleFunc("GET /random", handleRandom(dict))
+	mux.HandleFunc("GET /define", handleDefine(dict))
+	mux.HandleFunc("GET /synonyms", handleSynonyms(dict))
+	mux.HandleFunc("GET /translate", handleTranslate(dict))
+	mux.HandleFunc("GET /health", handleHealth(dict, ":memory:"))
+	return mux
+}
+
+func benchRequest(b *testing.B, mux *http.ServeMux, path string) {
+	b.Helper()
+	req := httptest.NewRequest("GET", path, nil)
+	b.ResetTimer()
+	for b.Loop() {
+		w := httptest.NewRecorder()
+		mux.ServeHTTP(w, req)
+		if w.Code != 200 {
+			b.Fatalf("status %d for %s", w.Code, path)
+		}
+	}
+}
+
+func BenchmarkHTTPValid(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/valid?word=word0003&lang=en")
+}
+
+func BenchmarkHTTPRandom(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/random?lang=en")
+}
+
+func BenchmarkHTTPRandomFiltered(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/random?lang=en&pos=noun&min=5&max=10")
+}
+
+func BenchmarkHTTPDefine(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/define?word=word0003&lang=en")
+}
+
+func BenchmarkHTTPSynonyms(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/synonyms?word=word0003&lang=en")
+}
+
+func BenchmarkHTTPTranslate(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/translate?word=word0003&from=en&to=fr")
+}
+
+func BenchmarkHTTPHealth(b *testing.B) {
+	mux := setupBenchServer(b)
+	benchRequest(b, mux, "/health")
+}