refactor(json): replace seld/jsonlint with serde_json

Validate JSON syntax with serde_json's parse errors in JsonFile, and detect
duplicate keys in ConfigValidator with a hand-written serde visitor, dropping
the now-unused JsonParser/Lexer/DuplicateKeyException ports. ParsingException
is kept as the thrown error type and downcast signal.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

1 files changed, 12 insertions, 6 deletions

diff --git a/crates/shirabe-external-packages/src/seld/json_lint.rs b/crates/shirabe-external-packages/src/seld/json_lint.rs
index 8027cb2..2165c8f 100644
--- a/crates/shirabe-external-packages/src/seld/json_lint.rs
+++ b/crates/shirabe-external-packages/src/seld/json_lint.rs
@@ -1,9 +1,15 @@
-pub mod duplicate_key_exception;
-pub mod json_parser;
-pub mod lexer;
+//! Partial port of seld/jsonlint.
+//!
+//! The parser, lexer, and duplicate-key exception (`JsonParser`, `Lexer`,
+//! `DuplicateKeyException`) are intentionally not ported: JSON syntax validation now relies on
+//! serde_json, and duplicate-key detection is done with a hand-written serde visitor, so
+//! jsonlint's own parsing machinery is no longer needed.
+//!
+//! `ParsingException` is kept because it is the exception type thrown for invalid JSON and is
+//! matched (via downcast) across the codebase as an error-kind signal; it also carries detail
+//! such as the error line. Porting it keeps both the thrown exception class and the information
+//! it carries unchanged.
+
 pub mod parsing_exception;
 
-pub use duplicate_key_exception::*;
-pub use json_parser::*;
-pub use lexer::*;
 pub use parsing_exception::*;