Update spec repo URL references (cdx-file-format-spec)

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "spec"]
 	path = spec
-	url = https://github.com/Entrolution/codex-file-format-spec.git
+	url = https://github.com/Entrolution/cdx-file-format-spec.git

CONTRIBUTING.md

@@ -142,7 +142,7 @@ src/
 
 ## Specification Reference
 
-This library implements the [CDX Document Format Specification](https://github.com/Entrolution/codex-file-format-spec). When implementing new features:
+This library implements the [CDX Document Format Specification](https://github.com/Entrolution/cdx-file-format-spec). When implementing new features:
 
 - Reference the relevant spec section
 - Note any deviations or extensions

README.md

@@ -7,7 +7,7 @@
 
 # cdx-core
 
-Core Rust library for reading, writing, and validating [CDX Document Format](https://github.com/Entrolution/codex-file-format-spec) (`.cdx`) files.
+Core Rust library for reading, writing, and validating [CDX Document Format](https://github.com/Entrolution/cdx-file-format-spec) (`.cdx`) files.
 
 ## Overview
 
@@ -161,7 +161,7 @@ cargo run --example open_and_verify path/to/document.cdx
 
 ## Specification Compliance
 
-This library implements the [CDX Document Format Specification v0.1](https://github.com/Entrolution/codex-file-format-spec).
+This library implements the [CDX Document Format Specification v0.1](https://github.com/Entrolution/cdx-file-format-spec).
 
 ### Module Status
 

docs/conformance-matrix.md

@@ -1,6 +1,6 @@
 # CDX Specification Conformance Matrix
 
-This document maps requirements from the [CDX File Format Specification](../codex-file-format-spec/) to test coverage in cdx-core.
+This document maps requirements from the [CDX File Format Specification](../cdx-file-format-spec/) to test coverage in cdx-core.
 
 ## Legend