fix(biome): add .css to default fileTypes for CSS language support

Biome 2.x fully supports CSS parsing, formatting, linting, and assist
actions via its CLI and LSP proxy. The built-in Biome client config
did not include .css in its fileTypes array, causing OMP to skip Biome
for CSS files even when the project's biome.json enables CSS rules.

This change adds .css to the default fileTypes so that projects with
CSS files automatically route through Biome without needing a per-project
override of the full fileTypes array.

Closes #8735

packages/coding-agent/src/lsp/defaults.json

@@ -69,7 +69,7 @@
 	"biome": {
 		"command": "biome",
 		"args": ["lsp-proxy"],
-		"fileTypes": [".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs", ".json", ".jsonc"],
+		"fileTypes": [".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs", ".json", ".jsonc", ".css"],
 		"rootMarkers": ["biome.json", "biome.jsonc"],
 		"isLinter": true
 	},
@@ -502,4 +502,4 @@
 		"rootMarkers": [".swiftlint.yml", ".swiftlint.yaml", "Package.swift", "*.xcodeproj"],
 		"isLinter": true
 	}
-}
+}