feat: add --proxy flag for browser proxy configuration (#16)

* feat: add --proxy flag for browser proxy support

Add CLI flag to configure HTTP/SOCKS proxy for Playwright browser context.
Supports URL format with optional credentials: http://user:pass@host:port

* fix: improve proxy parsing error handling

- Handle malformed credentials (@ without :) by ignoring incomplete creds
- Replace unwrap() with expect() for better error messages
- Addresses Vercel bot code review suggestions

* Restaura cambios locales: soporte AGENT_BROWSER_HOME y timeout aumentado

- Agrega soporte para variable de entorno AGENT_BROWSER_HOME en connection.rs
- Aumenta timeout por defecto de 10s a 60s para conexiones más lentas

* feat: add --proxy flag for browser proxy configuration

Implements proxy support based on PR #16 with reviewer feedback:

Features:
- Parse proxy URLs: http://[user:pass@]host:port
- Support for HTTP, HTTPS, and SOCKS5 protocols
- Handle username-only auth (preserves username with empty password)
- Apply proxy to both standard and persistent contexts

Changes:
- cli/src/flags.rs: Add proxy flag parsing
- cli/src/main.rs: Add parse_proxy() with comprehensive tests
- cli/src/output.rs: Add --proxy to help output
- cli/src/commands.rs: Fix test helper to include proxy field
- src/types.ts: Add proxy to LaunchCommand interface
- src/protocol.ts: Add proxy validation schema
- src/browser.ts: Apply proxy to context creation

Tests:
- 7 unit tests for parse_proxy() covering all edge cases
- All Rust tests passing (69 tests)
- All TypeScript tests passing (168 tests)
- TypeScript typecheck passing

Resolves feedback from PR #16:
- Fixed username-only proxy handling (issue #2681046975)
- Added comprehensive unit tests
- Added --proxy to help documentation
- Used expect() instead of unwrap() for better error messages

* refactor: simplify parse_proxy function

- Remove redundant comments
- Extract server variable to reduce duplication
- Inline trivial username/password variables

All 7 proxy tests still passing.

cli/src/main.rs

@@ -23,6 +23,36 @@ use flags::{clean_args, parse_flags};
 use install::run_install;
 use output::{print_command_help, print_help, print_response, print_version};
 
+fn parse_proxy(proxy_str: &str) -> serde_json::Value {
+    let Some(protocol_end) = proxy_str.find("://") else {
+        return json!({ "server": proxy_str });
+    };
+    let protocol = &proxy_str[..protocol_end + 3];
+    let rest = &proxy_str[protocol_end + 3..];
+
+    let Some(at_pos) = rest.rfind('@') else {
+        return json!({ "server": proxy_str });
+    };
+
+    let creds = &rest[..at_pos];
+    let server_part = &rest[at_pos + 1..];
+    let server = format!("{}{}", protocol, server_part);
+
+    let Some(colon_pos) = creds.find(':') else {
+        return json!({
+            "server": server,
+            "username": creds,
+            "password": ""
+        });
+    };
+
+    json!({
+        "server": server,
+        "username": &creds[..colon_pos],
+        "password": &creds[colon_pos + 1..]
+    })
+}
+
 fn run_session(args: &[String], session: &str, json_mode: bool) {
     let subcommand = args.get(1).map(|s| s.as_str());
 
@@ -234,17 +264,24 @@ fn main() {
         }
     }
 
-    // Launch headed browser if --headed flag is set (without CDP)
-    if flags.headed && flags.cdp.is_none() {
-        let launch_cmd = json!({
+    // Launch headed browser or proxy if flags are set (without CDP)
+    if (flags.headed || flags.proxy.is_some()) && flags.cdp.is_none() {
+        let mut launch_cmd = json!({
             "id": gen_id(),
             "action": "launch",
-            "headless": false
+            "headless": !flags.headed
         });
 
+        if let Some(ref proxy_str) = flags.proxy {
+            let proxy_obj = parse_proxy(proxy_str);
+            launch_cmd.as_object_mut()
+                .expect("json! macro guarantees object type")
+                .insert("proxy".to_string(), proxy_obj);
+        }
+
         if let Err(e) = send_command(launch_cmd, &flags.session) {
             if !flags.json {
-                eprintln!("\x1b[33m⚠\x1b[0m Could not launch headed browser: {}", e);
+                eprintln!("\x1b[33m⚠\x1b[0m Could not configure browser: {}", e);
             }
         }
     }
@@ -267,3 +304,62 @@ fn main() {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_proxy_simple() {
+        let result = parse_proxy("http://proxy.com:8080");
+        assert_eq!(result["server"], "http://proxy.com:8080");
+        assert!(result.get("username").is_none());
+        assert!(result.get("password").is_none());
+    }
+
+    #[test]
+    fn test_parse_proxy_with_auth() {
+        let result = parse_proxy("http://user:pass@proxy.com:8080");
+        assert_eq!(result["server"], "http://proxy.com:8080");
+        assert_eq!(result["username"], "user");
+        assert_eq!(result["password"], "pass");
+    }
+
+    #[test]
+    fn test_parse_proxy_username_only() {
+        let result = parse_proxy("http://user@proxy.com:8080");
+        assert_eq!(result["server"], "http://proxy.com:8080");
+        assert_eq!(result["username"], "user");
+        assert_eq!(result["password"], "");
+    }
+
+    #[test]
+    fn test_parse_proxy_no_protocol() {
+        let result = parse_proxy("proxy.com:8080");
+        assert_eq!(result["server"], "proxy.com:8080");
+        assert!(result.get("username").is_none());
+    }
+
+    #[test]
+    fn test_parse_proxy_socks5() {
+        let result = parse_proxy("socks5://proxy.com:1080");
+        assert_eq!(result["server"], "socks5://proxy.com:1080");
+        assert!(result.get("username").is_none());
+    }
+
+    #[test]
+    fn test_parse_proxy_socks5_with_auth() {
+        let result = parse_proxy("socks5://admin:secret@proxy.com:1080");
+        assert_eq!(result["server"], "socks5://proxy.com:1080");
+        assert_eq!(result["username"], "admin");
+        assert_eq!(result["password"], "secret");
+    }
+
+    #[test]
+    fn test_parse_proxy_complex_password() {
+        let result = parse_proxy("http://user:p@ss:w0rd@proxy.com:8080");
+        assert_eq!(result["server"], "http://proxy.com:8080");
+        assert_eq!(result["username"], "user");
+        assert_eq!(result["password"], "p@ss:w0rd");
+    }
+}