docs: add CONTRIBUTING.md guide

[dashitongzhi]

Summary\n\nAdded a comprehensive CONTRIBUTING.md to help contributors get started:\n\n- Development setup instructions (Node.js, pnpm)\n- Project structure overview\n- Code style guidelines\n- PR process documentation\n\nThis improves the contributor experience for new community members.

[Copilot]

Pull request overview

Adds a new CONTRIBUTING.md intended to guide new contributors through setup, project orientation, coding standards, and the PR process.

Changes:

• Introduces contributor onboarding documentation (setup, structure, workflow).
• Documents suggested code style and testing steps.
• Defines a basic pull request and issue reporting process.

Comments suppressed due to low confidence (6)

CONTRIBUTING.md:15

• pnpm install is referenced here, but the repo uses npm (package-lock.json) for the VitePress docs and Deno tasks for the app. Update this section to the correct install steps (e.g., npm install for docs/ tooling, and/or note that Deno fetches deps automatically).

2. **Install dependencies**
   ```bash
   pnpm install

**CONTRIBUTING.md:26**
* `pnpm dev` doesn’t appear to exist in this repo (package.json only defines `docs:*` scripts; the app is run via `deno task start`). Please replace this with the actual dev command(s) contributors should use.

4. Run in development mode

   pnpm dev

**CONTRIBUTING.md:35**
* The project structure example lists `src/bot/` (Telegram handlers), but this repository doesn’t have that directory and instead has areas like `src/controllers/`, `src/api/`, and `src/server.ts`. Please update this tree to reflect the actual layout so contributors can navigate the codebase correctly.

ai-trend-publish/
├── src/
│ ├── bot/ # Telegram bot handlers
│ ├── services/ # Content fetching and processing
│ └── utils/ # Helper functions

**CONTRIBUTING.md:50**
* `pnpm lint` is referenced here, but this repo doesn’t define a `lint` script in package.json and the main workflow uses Deno. Please update the lint guidance to the actual command(s) used here (e.g., `deno lint` / any configured Deno task).

2. Code style
   • Use TypeScript for all new code
   • Run pnpm lint before committing
   • Write self-documenting code

**CONTRIBUTING.md:56**
* The test instructions use `pnpm test` / `pnpm lint`, but the repo’s existing tasks are Deno-based (`deno task test`, etc.) and docs use `npm run docs:*`. Please replace these commands with the ones that actually exist so contributors can verify changes.

3. Test your changes

   pnpm test
   pnpm lint

**CONTRIBUTING.md:21**
* The `.env` setup comment mentions adding a Telegram bot token, but `.env.example` is oriented around LLM providers, Weixin config, and other services (no Telegram variables). Please update this guidance to reference the actual env vars contributors need to set (and consider linking to `ENV_CONFIGURATION.md` if that’s the canonical reference).

3. Environment configuration

   cp .env.example .env
   # Edit .env with your Telegram bot token and API keys

</details>



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