Remove ABC interface classes and inline method docstrings (#572)

## Summary

This PR removes ABC interface classes that were only used to store
docstrings and moves all documentation directly to the implementation
methods. This simplifies the codebase by eliminating unnecessary
abstraction layers while preserving all documentation.

## Changes Made

### Removed Interface Classes
- Deleted `pinecone/db_data/interfaces.py` (IndexInterface)
- Deleted `pinecone/db_data/index_asyncio_interface.py`
(IndexAsyncioInterface)
- Deleted `pinecone/pinecone_interface_asyncio.py`
(PineconeAsyncioDBControlInterface)

### Updated Implementation Classes
- `pinecone/db_data/index.py` - Removed IndexInterface inheritance
- `pinecone/db_data/index_asyncio.py` - Added docstrings to all methods,
removed IndexAsyncioInterface inheritance
- `pinecone/pinecone_asyncio.py` - Added docstrings to all methods,
removed PineconeAsyncioDBControlInterface inheritance

## Why These Changes Were Made

The ABC interface classes (`IndexInterface`, `IndexAsyncioInterface`,
and `PineconeAsyncioDBControlInterface`) were serving no functional
purpose beyond storing docstrings. They added unnecessary complexity to
the codebase without providing any runtime benefits:

- No type checking or enforcement (methods were already implemented)
- No shared implementation (all methods were abstract with `pass`)
- Documentation was the only content in these classes

By inlining the docstrings directly into the implementation methods, we:
- Reduce code complexity (net -1,503 lines)
- Improve maintainability (documentation lives with implementation)
- Eliminate unnecessary inheritance chains
- Maintain full API documentation (all docstrings preserved)

## Implementation Details

1. **Docstring Migration**: All docstrings were moved from interface
methods to their corresponding implementation methods, maintaining:
- Full RST syntax compatibility (`.. code-block::`, `.. admonition::`,
`:param:`, `:type:`, etc.)
   - All code examples and usage patterns
   - Parameter descriptions and return type documentation

2. **Import Cleanup**: Removed all imports of the interface classes from
implementation files

3. **Inheritance Removal**: Removed interface class inheritance from:
   - `Index(PluginAware, IndexInterface)` → `Index(PluginAware)`
   - `_IndexAsyncio(IndexAsyncioInterface)` → `_IndexAsyncio`
- `PineconeAsyncio(PineconeAsyncioDBControlInterface)` →
`PineconeAsyncio`

4. **Verification**: 
   - All docstrings verified for consistency with method implementations
   - Code examples validated for syntactic correctness
   - RST syntax verified for Sphinx compatibility
   - No linter errors introduced

## Impact

- **Lines Changed**: -1,503 net lines (removed 3,240, added 1,737)
- **Files Changed**: 6 files (3 deleted, 3 modified)
- **Breaking Changes**: None - all public APIs remain unchanged
- **Documentation**: Fully preserved - all docstrings maintained

---

*This PR was generated with Vibe Kanban and Cursor.*

Author: jhamon

pinecone/db_data/index.py

@@ -31,7 +31,6 @@
     UpsertResponse,
     UpdateResponse,
 )
-from .interfaces import IndexInterface
 from .request_factory import IndexRequestFactory
 from .types import (
     SparseVectorTypedDict,
@@ -131,7 +130,7 @@ def __getattr__(self, name: str) -> Any:
         return getattr(self._apply_result, name)
 
 
-class Index(PluginAware, IndexInterface):
+class Index(PluginAware):
     """
     A client for interacting with a Pinecone index via REST API.
     For improved performance, use the Pinecone GRPC index client.