Add CLI documentation to the Overview section (#1224)

This PR adds a new CLI documentation section to the Overview in the
docs. The CLI section is placed after the API section as requested.

The documentation includes:
- Installation instructions
- Authentication methods
- Basic usage examples
- Available commands with descriptions
- Common workflows
- Environment variables
- Use cases and benefits

This provides a good starting point for users to understand and use the
Codegen CLI.

---

[💻 View my work](https://codegen.com/agent/trace/77692) • 👤 Initiated by
@rushilpatel0 • [About Codegen](https://codegen.com)
[⛔ Remove Codegen from
PR](https://codegen.com/agent/trace/77692/remove-from-pr) • [🚫 Ban
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---------

Co-authored-by: codegen-sh[bot] <131295404+codegen-sh[bot]@users.noreply.github.com>
Co-authored-by: Rushil Patel <[email protected]>

Author: codegen-sh[bot]

docs/docs.json

@@ -18,6 +18,7 @@
             "pages": [
               "introduction/overview",
               "introduction/api",
+              "introduction/cli",
               "introduction/prompting",
               "introduction/community",
               "introduction/about",

docs/introduction/cli.mdx

@@ -0,0 +1,141 @@
+---
+title: "Codegen CLI"
+sidebarTitle: "CLI"
+icon: "terminal"
+iconType: "solid"
+---
+
+# Codegen CLI Manual
+
+Welcome to the Codegen CLI documentation. This guide covers all available commands and their usage patterns.
+
+## Installation
+
+```bash
+uv tool install codegen
+```
+
+## Initialization
+
+```bash
+codegen login
+```
+
+## CLI Reference
+
+### `codegen` (root)
+
+**Description:** Launches the interactive TUI if no subcommand is provided.
+
+---
+
+### `codegen agent`
+
+**Description:** Create a new agent run with a prompt, fetch an existing agent run by ID, or pull PR branch.
+
+**Usage Patterns:**
+- **Create run:** `codegen agent --prompt "Your prompt"`
+- **Get run JSON:** `codegen agent --id 123 --json`
+- **Pull PR branch:** `codegen agent --id 123 pull`
+
+**Options:**
+- `--prompt, -p TEXT` The prompt to send to the agent (mutually exclusive with --id unless using create)
+- `--id INT` Agent run ID to fetch or pull
+- `--json` Output raw JSON response when fetching (flag)
+- `--org-id INT` Organization ID (defaults to CODEGEN_API_TOKEN/REPOSITORY_ORG_ID or auto-detect)
+- `--model TEXT` Model to use for this agent run (optional)
+- `--repo-id INT` Repository ID to use for this agent run (optional)
+
+**Positional Actions:**
+- `pull` Pull the PR branch associated with an agent run (requires --id)
+
+---
+
+### `codegen agents`
+
+**Description:** List and manage agent runs.
+
+**Usage Patterns:**
+- **List runs:** `codegen agents list`
+- **Get run details:** `codegen agents get 123`
+
+**Options:**
+- `--org-id INT` Organization ID (defaults to CODEGEN_ORG_ID/REPOSITORY_ORG_ID or auto-detect)
+- `--limit INT` Maximum number of runs to return (default: 10)
+- `--json` Output raw JSON response (flag)
+
+---
+
+### `codegen login`
+
+**Description:** Store authentication token.
+
+**Usage Patterns:**
+- **Interactive login:** `codegen login`
+- **Token login:** `codegen login --token YOUR_API_TOKEN`
+
+**Options:**
+- `--token TEXT` API token to store
+- `--no-verify` Skip token verification (flag)
+
+---
+
+### `codegen logout`
+
+**Description:** Clear stored authentication token.
+
+**Usage Pattern:**
+- `codegen logout`
+
+---
+
+### `codegen org`
+
+**Description:** Manage and switch between organizations.
+
+**Usage Patterns:**
+- **List organizations:** `codegen org list`
+- **Switch organization:** `codegen org switch ORG_ID`
+- **Get current organization:** `codegen org current`
+
+**Options:**
+- `--json` Output raw JSON response (flag)
+
+---
+
+### `codegen repo`
+
+**Description:** Manage repository configuration and environment variables.
+
+**Usage Patterns:**
+- **List repositories:** `codegen repo list`
+- **Configure repository:** `codegen repo config REPO_NAME`
+- **Get repository details:** `codegen repo get REPO_ID`
+
+**Options:**
+- `--org-id INT` Organization ID (defaults to CODEGEN_ORG_ID or auto-detect)
+- `--json` Output raw JSON response (flag)
+
+---
+
+## Get Started
+
+import {
+  COMMUNITY_SLACK_URL,
+  CODEGEN_SDK_GITHUB_URL,
+} from "/snippets/links.mdx";
+
+<CardGroup cols={2}>
+  <Card title="Create Account" icon="user-plus" href="https://codegen.sh/login">
+    Sign up for a free account and get your API token.
+  </Card>
+  <Card title="Join our Slack" icon="slack" href={COMMUNITY_SLACK_URL}>
+    Get help and connect with the Codegen community.
+  </Card>
+  <Card title="Tutorials" icon="diagram-project" href="/tutorials/at-a-glance">
+    Learn how to use Codegen for common code transformation tasks.
+  </Card>
+  <Card title="View on GitHub" icon="github" href={CODEGEN_SDK_GITHUB_URL}>
+    Star us on GitHub and contribute to the project.
+  </Card>
+</CardGroup>