mcp_indexer_server: fix: make repo_search tolerant of mcp-remote args schema

[voarsh2]

The qdrant-indexer MCP server was emitting a flat schema for repo_search
(query, limit, include_snippet, collection, etc.), but the Windsurf/Claude
qdrant-indexer integration (via mcp-remote) was still modeling this tool as
taking {args, kwargs}. This mismatch surfaced as:

• Client: repo_searchArguments.args is required
• Server: repo_search() got an unexpected keyword argument 'args'

To make repo_search compatible with both direct FastMCP clients and the
mcp-remote wrapper, we:

• Added an optional args: Any = None parameter to repo_search, treated as
  a no-op "compatibility shim" for clients that insist on sending args/kwargs.
• Left all existing named parameters and kwargs handling unchanged so
  direct callers and internal wrappers keep working as before.

Net effect:

• repo_search now tolerates the mcp-remote/Claude {args, kwargs} calling
  convention without breaking direct FastMCP usage.