aicc-py 0.1.0: initial SDK

- protocol.py: pydantic models for all AICC message types (envelope,
  session_init, tool_call, tool_result, event, error, heartbeat)
- bridge.py: Bridge with @bridge.tool registration, capability checks,
  session management, serve_forever
- client.py: AICCClient with single background reader (safe on
  concurrent transports like WebSocket), call_tool, events, manifest
- tool.py: @tool decorator with schema generation from type hints
- schema.py: JSON Schema generation (str/int/float/bool, list, dict,
  Optional, pydantic models)
- transport: Transport protocol, InProcessTransport, WebSocket client+server
- tests: 12 passing (integration, schema, websocket roundtrip)
- examples: bridge_minimal.py + agent_minimal.py (verified end-to-end)

aicc/errors.py

@@ -0,0 +1,35 @@
+"""AICC exception hierarchy."""
+
+from __future__ import annotations
+
+from aicc.protocol import ErrorCode
+
+
+class AICCError(Exception):
+    """Base for all AICC SDK errors."""
+
+
+class ProtocolError(AICCError):
+    """Protocol-level error (version mismatch, malformed message)."""
+
+
+class ConnectionError_(AICCError):
+    """Transport / session connection failure."""
+
+
+class SessionExpiredError(AICCError):
+    """Session id is unknown or closed."""
+
+
+class ToolError(AICCError):
+    """Tool execution failure surfaced by the bridge."""
+
+    def __init__(self, code: ErrorCode, message: str, retryable: bool):
+        super().__init__(message)
+        self.code = code
+        self.message = message
+        self.retryable = retryable
+
+
+class CapabilityError(AICCError):
+    """Tool requires a capability the agent does not hold."""