Improve name_ipa generation and add IPA audit

AGENTS.md

@@ -46,6 +46,7 @@ This guide explains how automation agents and human contributors should work wit
 - **Full suite** – `make test-all` runs unit then integration tests sequentially. Set `RUST_LOG=debug` to inspect SQL queries during debugging.
 - **Linting and formatting** – Run `cargo fmt` and `cargo clippy --all-targets --all-features` before committing. Resolve new Clippy warnings unless an existing `#![allow]` covers the case.
 - **Data verification** – Execute `cargo run -p data_validator` whenever CSVs change and record results in pull requests.
+- **IPA coverage audit** – Execute `make ipa-audit` when English or romanized CSV names change. This is a read-only report for `data/2!lines.csv`, `data/3!stations.csv`, and `data/4!types.csv`; it does not fail validation, but highlights unresolved tokens and example names so the IPA dictionary can be extended deliberately.
 
 ## gRPC Endpoint Overview
 - **Stations** – `GetStationById`, `GetStationByIdList`, `GetStationsByGroupId`, `GetStationsByCoordinates`, `GetStationsByLineId`, `GetStationsByName`, `GetStationsByLineGroupId`. `QueryInteractor` enriches stations with lines, companies, station numbers, and train types.

Makefile

@@ -1,14 +1,15 @@
 # StationAPI Makefile
 # Cargoを使ったテスト実行のためのシンプルなタスク定義
 
-.PHONY: test test-unit test-integration test-all clean help
+.PHONY: test test-unit test-integration test-all ipa-audit clean help
 
 # デフォルトターゲット
 help:
 	@echo "Available targets:"
 	@echo "  test-unit        - Run unit tests only (no database required)"
 	@echo "  test-integration - Run integration tests (requires PostgreSQL)"
 	@echo "  test-all         - Run all tests"
+	@echo "  ipa-audit        - Print IPA coverage report for English/romanized CSV names"
 	@echo "  test             - Alias for test-unit"
 	@echo "  clean            - Clean build artifacts"
 	@echo ""
@@ -30,6 +31,11 @@ test-integration:
 # 全てのテストを実行
 test-all: test-unit test-integration
 
+ipa-audit:
+	@echo "Printing IPA coverage report..."
+	rustc tools/ipa_audit.rs -o /tmp/stationapi-ipa-audit
+	/tmp/stationapi-ipa-audit
+
 # デフォルトはユニットテスト
 test: test-unit