refactor!: modernize toolchain and add search command

[nitaking]

Summary

• pnpm 移行: yarn → pnpm、Node.js >= 20 に引き上げ
• フレームワーク刷新: oclif v1 → v4、TypeScript 3 → 5、ESM 化（inquirer v9, execa v9）
• リンター移行: tslint → eslint (flat config)
• テスト移行: mocha/chai/nyc → vitest（10 tests passing）
• CI 移行: CircleCI → GitHub Actions（Node 20/22 マトリクス）
• セキュリティ: pnpm audit 脆弱性ゼロ
• 新機能: gitmoji search コマンド追加（引数あり: 静的検索、引数なし: インタラクティブ）

BREAKING CHANGE

Node.js >= 20 が必須になりました。

Test plan

• pnpm install && pnpm build が成功すること
• pnpm test で 10 テストが全パスすること
• pnpm audit が脆弱性ゼロであること
• ./bin/run list でgitmoji一覧が表示されること
• ./bin/run search bug で静的検索が動作すること
• ./bin/run search でインタラクティブ検索が動作すること
• ./bin/run commit でインタラクティブコミットが動作すること

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR modernizes the gitmoji-c CLI’s toolchain (Node 20+, pnpm, TypeScript 5, ESM, oclif v4), migrates linting/testing/CI, and adds a new gitmoji search command (static search with args, interactive without args).

Changes:

• Migrates CLI framework and runtime to oclif v4 + ESM (including updated bin entrypoint) and updates TypeScript target/module settings.
• Replaces the legacy test setup with Vitest and adds new unit/integration tests for utils/prompt and list/search commands.
• Adds a new search command and updates gitmoji data fetch URL.

Reviewed changes

Copilot reviewed 21 out of 27 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
yarn.lock	Removed Yarn lockfile as part of pnpm migration.
pnpm-lock.yaml	pnpm lockfile is now the dependency source of truth.
package.json	Updates dependencies (oclif v4, TS5, Vitest, ESLint), sets ESM/module type, Node >= 20, and adds pnpm metadata/scripts.
tsconfig.json	Updates TS module/target for modern Node/ESM output and adds stricter consistency options.
eslint.config.mjs	Adds ESLint flat config with TypeScript rules.
vitest.config.ts	Adds Vitest configuration (globals + timeout).
bin/run	Switches CLI entrypoint to oclif v4 execute() in ESM.
src/index.ts	Updates exported run entry to @oclif/core.
src/utils.ts	Updates remote gitmoji JSON path and simplifies axios client config.
src/prompt.ts	Refactors prompt question definitions for ESM + cleaner filtering/choice mapping.
src/commands/list.ts	Migrates list command to oclif v4 args/flags parsing and simplifies printing/search.
src/commands/search.ts	Adds new search command with static and interactive (autocomplete) modes.
src/commands/commit.ts	Migrates commit command to oclif v4 + ESM and updates inquirer/autocomplete usage.
test/utils.test.ts	Adds Vitest tests for gitmojis() (currently network-backed).
test/prompt.test.ts	Adds Vitest tests for prompt question behavior (currently network-backed via gitmojis()).
test/commands/list.test.ts	Adds integration tests executing CLI for list behavior (currently network-backed).
test/commands/search.test.ts	Adds integration tests executing CLI for search behavior (currently network-backed).
test/commands/hello.test.ts	Removes legacy oclif v1 hello command test.
src/commands/hello.ts	Removes legacy hidden hello command.
.github/workflows/ci.yml	Adds GitHub Actions CI (Node 20/22) with pnpm + build/test/audit steps.
.circleci/config.yml	Removes CircleCI configuration.
tslint.json	Removes TSLint config as part of ESLint migration.
test/mocha.opts	Removes Mocha options as part of Vitest migration.
test/tsconfig.json	Removes test TS project config (no longer used by Mocha/TSLint flow).
.node-version	Adds Node version pin (20).
.gitignore	Ignores tsconfig.tsbuildinfo from TS build mode.

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