[router] add tool parser base structure and partial json parser (#9482)

sgl-router/src/tool_parser/mod.rs

@@ -0,0 +1,20 @@
+/// Tool parser module for handling function/tool calls in model outputs
+///
+/// This module provides infrastructure for parsing tool calls from various model formats.
+/// Phase 1 focuses on core infrastructure: types, traits, registry, and partial JSON parsing.
+pub mod errors;
+pub mod partial_json;
+pub mod registry;
+pub mod state;
+pub mod traits;
+pub mod types;
+
+#[cfg(test)]
+mod tests;
+
+// Re-export commonly used types
+pub use errors::{ToolParserError, ToolParserResult};
+pub use registry::ParserRegistry;
+pub use state::{ParsePhase, ParseState};
+pub use traits::{PartialJsonParser, ToolParser};
+pub use types::{FunctionCall, PartialToolCall, StreamResult, TokenConfig, ToolCall};