refactor: move brother_node development artifact to dev/test-nodes subdirectory

Development Artifact Cleanup:
✅ BROTHER_NODE REORGANIZATION: Moved development test node to appropriate location
- dev/test-nodes/brother_node/: Moved from root directory for better organization
- Contains development configuration, test logs, and test chain data
- No impact on production systems - purely development/testing artifact

✅ DEVELOPMENT ARTIFACTS IDENTIFIED:
- Chain ID: aitbc-brother-chain (test/development chain)
- Ports: 8010 (P2P) and 8011 (RPC) - different from production
- Environment: .env file with test configuration
- Logs: rpc.log and node.log from development testing session (March 15, 2026)

✅ ROOT DIRECTORY CLEANUP: Removed development clutter from production directory
- brother_node/ moved to dev/test-nodes/brother_node/
- Root directory now contains only production-ready components
- Development artifacts properly organized in dev/ subdirectory

DIRECTORY STRUCTURE IMPROVEMENT:
📁 dev/test-nodes/: Development and testing node configurations
🏗️ Root Directory: Clean production structure with only essential components
🧪 Development Isolation: Test environments separated from production

BENEFITS:
✅ Clean Production Directory: No development artifacts in root
✅ Better Organization: Development nodes grouped in dev/ subdirectory
✅ Clear Separation: Production vs development environments clearly distinguished
✅ Maintainability: Easier to identify and manage development components

RESULT: Successfully moved brother_node development artifact to dev/test-nodes/ subdirectory, cleaning up the root directory while preserving development testing environment for future use.

dev/env/cli_env/lib/python3.13/site-packages/dotenv/variables.py

@@ -0,0 +1,86 @@
+import re
+from abc import ABCMeta, abstractmethod
+from typing import Iterator, Mapping, Optional, Pattern
+
+_posix_variable: Pattern[str] = re.compile(
+    r"""
+    \$\{
+        (?P<name>[^\}:]*)
+        (?::-
+            (?P<default>[^\}]*)
+        )?
+    \}
+    """,
+    re.VERBOSE,
+)
+
+
+class Atom(metaclass=ABCMeta):
+    def __ne__(self, other: object) -> bool:
+        result = self.__eq__(other)
+        if result is NotImplemented:
+            return NotImplemented
+        return not result
+
+    @abstractmethod
+    def resolve(self, env: Mapping[str, Optional[str]]) -> str: ...
+
+
+class Literal(Atom):
+    def __init__(self, value: str) -> None:
+        self.value = value
+
+    def __repr__(self) -> str:
+        return f"Literal(value={self.value})"
+
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+        return self.value == other.value
+
+    def __hash__(self) -> int:
+        return hash((self.__class__, self.value))
+
+    def resolve(self, env: Mapping[str, Optional[str]]) -> str:
+        return self.value
+
+
+class Variable(Atom):
+    def __init__(self, name: str, default: Optional[str]) -> None:
+        self.name = name
+        self.default = default
+
+    def __repr__(self) -> str:
+        return f"Variable(name={self.name}, default={self.default})"
+
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+        return (self.name, self.default) == (other.name, other.default)
+
+    def __hash__(self) -> int:
+        return hash((self.__class__, self.name, self.default))
+
+    def resolve(self, env: Mapping[str, Optional[str]]) -> str:
+        default = self.default if self.default is not None else ""
+        result = env.get(self.name, default)
+        return result if result is not None else ""
+
+
+def parse_variables(value: str) -> Iterator[Atom]:
+    cursor = 0
+
+    for match in _posix_variable.finditer(value):
+        (start, end) = match.span()
+        name = match["name"]
+        default = match["default"]
+
+        if start > cursor:
+            yield Literal(value=value[cursor:start])
+
+        yield Variable(name=name, default=default)
+        cursor = end
+
+    length = len(value)
+    if cursor < length:
+        yield Literal(value=value[cursor:length])