fix: AP-1 percent-encode url() creds, AP-2 reject next(session=) collision

AP-1: url()/aiohttp() percent-encode user/password so reserved chars (/ # ? @) produce a
valid url, mirroring the parse-side unquote. AP-2: next(session=...) raises a clear
ValueError instead of an opaque str.format TypeError. net.current_ip uses
json(content_type=None) + dict guard.

Signed-off-by: disqualifier <dev@disqualifier.me>

src/aioproxies/manager.py

@@ -125,6 +125,10 @@ class AioProxies:
         if self._static is not None:
             return self._static
         if self.template is not None:
+            if "session" in fields:
+                # `session` is auto-filled with a fresh id; a caller-supplied one would
+                # collide in str.format with an opaque TypeError — reject it clearly
+                raise ValueError("'session' is filled automatically; do not pass it to next()")
             try:
                 filled = self.template.format(session=self.session_id(), **fields)
             except (KeyError, IndexError) as exc:

src/aioproxies/net.py

@@ -37,8 +37,10 @@ async def current_ip(
     try:
         async with aiohttp.ClientSession(timeout=t) as session:
             async with session.get(test_url, proxy=p.url()) as resp:
-                data = await resp.json()
-                return data.get("ip")
+                # content_type=None: an echo endpoint may return text/plain json; the
+                # default would raise ContentTypeError and silently return None
+                data = await resp.json(content_type=None)
+                return data.get("ip") if isinstance(data, dict) else None
     except Exception as exc:
         log.warning("ip check failed: %s", exc)
         return None

src/aioproxies/proxy.py

@@ -13,7 +13,7 @@ input shape. `canonical_key()` extends that to dict/url forms.
 """
 from dataclasses import dataclass
 from typing import Dict, Optional, Union
-from urllib.parse import unquote, urlsplit
+from urllib.parse import quote, unquote, urlsplit
 
 SCHEME_HTTP = "http"
 SCHEME_SOCKS5 = "socks5"
@@ -48,9 +48,15 @@ class Proxy:
         return f"{host}:{self.port}"
 
     def url(self, scheme: str = SCHEME_HTTP) -> str:
-        """render as a url, embedding auth when present"""
+        """render as a url, embedding auth when present
+
+        credentials are percent-encoded so reserved chars (/ # ? @ :) in a user or
+        password produce a valid url; this mirrors the unquote() on the parse side.
+        """
         if self.has_auth:
-            return f"{scheme}://{self.user}:{self.password}@{self.host}:{self.port}"
+            user = quote(str(self.user), safe="")
+            password = quote(str(self.password), safe="")
+            return f"{scheme}://{user}:{password}@{self.host}:{self.port}"
         return f"{scheme}://{self.host}:{self.port}"
 
     def aiohttp(self) -> Dict[str, str]: