fix(agents): keep import tokens outside URI scheme matches

tools/skills/agent-guidance-markdown.mjs

@@ -147,7 +147,7 @@ export function guidanceProse(markdown) {
             return ' ';
         if (node.nodeName === '#text')
             return node.value.replace(
-                /(?:\b[a-z][a-z\d+.-]*:(?![@\s])|\/\/)[^\s]*?(?=[)\]}>][.,;:!?]*@|\s|$)/giu,
+                /(?:(?<![@/\p{L}\p{N}_])[a-z][a-z\d+.-]*:(?![@\s])|\/\/)[^\s]*?(?=[)\]}>][.,;:!?]*@|\s|$)/giu,
                 ' '
             );
         const content = (node.childNodes ?? []).map(text).join('');

tools/skills/validate-agent-guidance.test.mjs

@@ -1507,7 +1507,6 @@ for (const boundary of [').', '];', '}']) {
 
 for (const uri of [
     '<mailto:user@example.com?subject=@docs/guide.md>',
-    'mailto:user@example.com?subject=@docs/guide.md',
     '<urn:example:@docs/guide.md>',
 ]) {
     test(`opaque URI is not a guidance import: ${uri}`, async (t) => {