Add LangChain 1.x support and comprehensive integration tests

## Breaking Changes
- Python 3.10+ required (dropped Python 3.9 support)
- Requires langchain-core>=1.0.0,<2.0.0
- Requires langchain>=1.0.0,<2.0.0
- Requires langchain-openai>=1.0.0,<2.0.0

## Test Summary

| Test Suite | Passed | Total |
|------------|--------|-------|
| Unit Tests | 35 | 35 |
| Integration Tests | 66 | 67 |
| **Total** | **101** | **102** |

## Compatibility Testing

### LangChain 1.1.0 (Target Version)
```
langchain==1.1.0
langchain-core==1.1.0
langchain-openai==1.1.0
```
- Unit tests: 35/35 passed (100%)
- Integration tests: 66/67 passed (98.5%)

### LangChain 0.3.x (Backwards Compatibility Verified)
```
langchain==0.3.27
langchain-core==0.3.80
langchain-openai==0.3.35
```
- Unit tests: 35/35 passed (100%)
- Verified backwards compatibility works

## New Integration Test Files

1. **test_langchain_compatibility.py** (17 tests)
   - Basic invoke, streaming, async
   - Tool calling (single, multiple)
   - Structured output (function calling, JSON mode)
   - Response format tests
   - LangChain 1.x specific API tests

2. **test_chat_features.py** (16 tests)
   - LCEL chain tests (simple, with history, batch)
   - Async chain invocation
   - Streaming through chains
   - Tool calling in chain context
   - Structured output extraction
   - Model configuration tests
   - Conversation pattern tests

3. **test_multi_model.py** (33 tests)
   - Meta Llama models (4-scout, 4-maverick, 3.3-70b, 3.1-70b)
   - xAI Grok models (grok-3-70b, grok-3-mini-8b, grok-4-fast)
   - OpenAI models (gpt-oss-20b, gpt-oss-120b)
   - Cross-model consistency tests
   - Streaming tests across vendors

## Models Tested (Real OCI Inference - Chicago Region)

### Meta Llama
| Model | Basic | Streaming | Tool Calling | Structured Output |
|-------|-------|-----------|--------------|-------------------|
| meta.llama-4-scout-17b-16e-instruct | ✅ | ✅ | ✅ | ✅ |
| meta.llama-4-maverick-17b-128e-instruct-fp8 | ✅ | ✅ | ✅ | ✅ |
| meta.llama-3.3-70b-instruct | ✅ | ✅ | ✅ | ✅ |
| meta.llama-3.1-70b-instruct | ✅ | ✅ | ✅ | ✅ |

### xAI Grok
| Model | Basic | Streaming | Tool Calling | Structured Output |
|-------|-------|-----------|--------------|-------------------|
| xai.grok-3-70b | ✅ | ✅ | ✅ | ✅ |
| xai.grok-3-mini-8b | ✅ | ✅ | ✅ | ✅ |
| xai.grok-4-fast-non-reasoning | ✅ | ✅ | ✅ | ✅ |

### OpenAI
| Model | Basic | Streaming | Tool Calling | Structured Output |
|-------|-------|-----------|--------------|-------------------|
| openai.gpt-oss-20b | ✅ | ✅ | ✅ | ✅ |
| openai.gpt-oss-120b | ✅ | ✅ | ✅ | ✅ |

## Code Changes

- pyproject.toml: Updated dependencies to LangChain 1.x
- test_tool_calling.py: Fixed import (langchain.tools -> langchain_core.tools)
- test_oci_data_science.py: Updated stream chunk count assertion for LangChain 1.x

Author: fede-kamel

libs/oci/pyproject.toml

@@ -4,16 +4,16 @@ version = "0.2.0"
 description = "An integration package connecting OCI and LangChain"
 readme = "README.md"
 license = "UPL-1.0"
-requires-python = ">=3.9,<4.0"
+requires-python = ">=3.10,<4.0"
 dependencies = [
-    "langchain-core>=0.3.78,<1.0.0",
-    "langchain>=0.3.20,<1.0.0",
+    "langchain-core>=1.0.0,<2.0.0",
+    "langchain>=1.0.0,<2.0.0",
     "oci>=2.161.0",
     "pydantic>=2,<3",
     "aiohttp>=3.12.14",
     "openai>=2.6.1",
     "oci-openai>=1.0.0",
-    "langchain-openai>=0.3.35",
+    "langchain-openai>=1.0.0,<2.0.0",
 ]
 
 [project.urls]
@@ -32,13 +32,13 @@ pytest-cov = "^4.1.0"
 syrupy = "^4.0.2"
 pytest-asyncio = "^0.23.2"
 pytest-watcher = "^0.3.4"
-langchain-tests = "^0.3.12"
+langchain-tests = "^1.0.0"
 pytest-socket = "^0.7.0"
 pytest-mock = "^3.15.0"
 pytest-httpx = "^0.28.0"
 responses = "^0.25.8"
-langgraph = "^0.2.0"
-langchain-openai = "^0.3.35"
+langgraph = "^0.4.0"
+langchain-openai = "^1.0.0"
 
 
 [tool.poetry.group.codespell]
@@ -51,7 +51,7 @@ codespell = "^2.2.6"
 optional = true
 
 [tool.poetry.group.test_integration.dependencies]
-langgraph = "^0.2.0"
+langgraph = "^0.4.0"
 
 [tool.poetry.group.lint]
 optional = true