fix: sanitize .env before loading to prevent token duplication (#8908)

When .env files become corrupted (e.g. concatenated KEY=VALUE pairs on
a single line due to concurrent writes or encoding issues), both
python-dotenv and load_env() would parse the entire concatenated string
as a single value. This caused bot tokens to appear duplicated up to 8×,
triggering InvalidToken errors from the Telegram API.

Root cause: _sanitize_env_lines() — which correctly splits concatenated
lines — was only called during save_env_value() writes, not during reads.

Fix:
- load_env() now calls _sanitize_env_lines() before parsing
- env_loader.load_hermes_dotenv() sanitizes the .env file on disk
  before python-dotenv reads it, so os.getenv() also returns clean values
- Added tests reproducing the exact corruption pattern from #8908

Closes #8908

hermes_cli/config.py

@@ -2384,7 +2384,13 @@ def save_config(config: Dict[str, Any]):
 
 
 def load_env() -> Dict[str, str]:
-    """Load environment variables from ~/.hermes/.env."""
+    """Load environment variables from ~/.hermes/.env.
+
+    Sanitizes lines before parsing so that corrupted files (e.g.
+    concatenated KEY=VALUE pairs on a single line) are handled
+    gracefully instead of producing mangled values such as duplicated
+    bot tokens.  See #8908.
+    """
     env_path = get_env_path()
     env_vars = {}
     
@@ -2393,11 +2399,15 @@ def load_env() -> Dict[str, str]:
         # fail on UTF-8 .env files. Use explicit UTF-8 only on Windows.
         open_kw = {"encoding": "utf-8", "errors": "replace"} if _IS_WINDOWS else {}
         with open(env_path, **open_kw) as f:
-            for line in f:
-                line = line.strip()
-                if line and not line.startswith('#') and '=' in line:
-                    key, _, value = line.partition('=')
-                    env_vars[key.strip()] = value.strip().strip('"\'')
+            raw_lines = f.readlines()
+        # Sanitize before parsing: split concatenated lines & drop stale
+        # placeholders so corrupted .env files don't produce invalid tokens.
+        lines = _sanitize_env_lines(raw_lines)
+        for line in lines:
+            line = line.strip()
+            if line and not line.startswith('#') and '=' in line:
+                key, _, value = line.partition('=')
+                env_vars[key.strip()] = value.strip().strip('"\'')
     
     return env_vars