feat: Package Public API Exports (GAP-5)

- Added __version__ that reads from package metadata with fallback
- Exports create_app from praisonai_platform.api.app
- Exports PlatformClient from praisonai_platform.client.platform_client
- Added __all__ list for clean star-imports
- Added usage example in module docstring
- Implements graceful error handling for missing db dependencies

Fixes #1376

Co-authored-by: MervinPraison <MervinPraison@users.noreply.github.com>

Author: praisonai-triage-agent[bot]

src/praisonai-platform/praisonai_platform/__init__.py

@@ -3,6 +3,53 @@
 
 A separate package providing multi-tenancy, authentication, issue tracking,
 and project management on top of the praisonaiagents core SDK.
+
+Quick-start usage::
+
+    from praisonai_platform import PlatformClient, create_app, __version__
+
+    # Start FastAPI app
+    app = create_app()
+
+    # Use SDK client
+    async with PlatformClient("http://localhost:8000") as client:
+        await client.register("user@example.com", "pass")
 """
 
-__version__ = "0.1.0"
+# Read version from package metadata
+try:
+    from importlib.metadata import version
+    __version__ = version("praisonai-platform")
+except ImportError:
+    # Fallback for older Python versions
+    try:
+        from importlib_metadata import version
+        __version__ = version("praisonai-platform")
+    except (ImportError, Exception):
+        __version__ = "0.1.0"
+
+# Lazy imports to handle missing dependencies gracefully
+def _get_create_app():
+    """Lazy import for create_app to handle missing db module."""
+    try:
+        from .api.app import create_app
+        return create_app
+    except ImportError as e:
+        error_msg = str(e)
+        def create_app(*args, **kwargs):
+            raise ImportError(
+                f"Cannot create FastAPI app due to missing dependencies: {error_msg}. "
+                "The database module may be incomplete or missing."
+            )
+        return create_app
+
+def _get_platform_client():
+    """Lazy import for PlatformClient."""
+    from .client.platform_client import PlatformClient
+    return PlatformClient
+
+# Public API exports using lazy imports
+create_app = _get_create_app()
+PlatformClient = _get_platform_client()
+
+__all__ = ["create_app", "PlatformClient", "__version__"]