fix(cli): respect --json flag on lint error paths

When lint encountered an error (e.g., invalid directory), it output
plain text even with --json, breaking JSON parsing pipelines for
agents. Now wraps the entire lint command in try-catch that emits
JSON errors when --json is set.

Reproducer:
  npx hyperframes lint --json /nonexistent/path
  # Was: plain text "Not a directory: /nonexistent/path"
  # Now: {"ok": false, "error": "Not a directory: /nonexistent/path", ...}

packages/cli/src/commands/lint.ts

@@ -15,63 +15,86 @@ export default defineCommand({
     json: { type: "boolean", description: "Output findings as JSON", default: false },
   },
   async run({ args }) {
-    const project = resolveProject(args.dir);
+    try {
-    const htmlFiles = walkDir(project.dir).filter((f) => f.endsWith(".html"));
+      const project = resolveProject(args.dir);
+      const htmlFiles = walkDir(project.dir).filter((f) => f.endsWith(".html"));
 
-    const allFindings: (HyperframeLintFinding & { file: string })[] = [];
+      const allFindings: (HyperframeLintFinding & { file: string })[] = [];
-    let totalErrors = 0;
+      let totalErrors = 0;
-    let totalWarnings = 0;
+      let totalWarnings = 0;
 
-    for (const file of htmlFiles) {
+      for (const file of htmlFiles) {
-      const html = readFileSync(join(project.dir, file), "utf-8");
+        const html = readFileSync(join(project.dir, file), "utf-8");
-      const result = lintHyperframeHtml(html, { filePath: file });
+        const result = lintHyperframeHtml(html, { filePath: file });
-      for (const f of result.findings) {
+        for (const f of result.findings) {
-        allFindings.push({ ...f, file });
+          allFindings.push({ ...f, file });
+        }
+        totalErrors += result.errorCount;
+        totalWarnings += result.warningCount;
+      }
+
+      if (args.json) {
+        console.log(
+          JSON.stringify(
+            withMeta({
+              ok: totalErrors === 0,
+              findings: allFindings,
+              errorCount: totalErrors,
+              warningCount: totalWarnings,
+              filesScanned: htmlFiles.length,
+            }),
+            null,
+            2,
+          ),
+        );
+        process.exit(totalErrors > 0 ? 1 : 0);
       }
-      totalErrors += result.errorCount;
-      totalWarnings += result.warningCount;
-    }
 
-    if (args.json) {
       console.log(
-        JSON.stringify(
+        `${c.accent("◆")}  Linting ${c.accent(project.name)} (${htmlFiles.length} HTML files)`,
-          withMeta({
-            ok: totalErrors === 0,
-            findings: allFindings,
-            errorCount: totalErrors,
-            warningCount: totalWarnings,
-            filesScanned: htmlFiles.length,
-          }),
-          null,
-          2,
-        ),
       );
+      console.log();
+
+      if (allFindings.length === 0) {
+        console.log(`${c.success("◇")}  ${c.success("0 errors, 0 warnings")}`);
+        return;
+      }
+
+      for (const finding of allFindings) {
+        const prefix = finding.severity === "error" ? c.error("✗") : c.warn("⚠");
+        const loc = finding.elementId ? ` ${c.accent(`[${finding.elementId}]`)}` : "";
+        console.log(
+          `${prefix}  ${c.bold(finding.code)}${loc}: ${finding.message} ${c.dim(finding.file)}`,
+        );
+        if (finding.fixHint) {
+          console.log(`   ${c.dim(`Fix: ${finding.fixHint}`)}`);
+        }
+      }
+
+      const summaryIcon = totalErrors > 0 ? c.error("◇") : c.success("◇");
+      console.log(`\n${summaryIcon}  ${totalErrors} error(s), ${totalWarnings} warning(s)`);
       process.exit(totalErrors > 0 ? 1 : 0);
-    }
+    } catch (err: unknown) {
-
+      const message = err instanceof Error ? err.message : String(err);
-    console.log(
+      if (args.json) {
-      `${c.accent("◆")}  Linting ${c.accent(project.name)} (${htmlFiles.length} HTML files)`,
+        console.log(
-    );
+          JSON.stringify(
-    console.log();
+            withMeta({
-
+              ok: false,
-    if (allFindings.length === 0) {
+              error: message,
-      console.log(`${c.success("◇")}  ${c.success("0 errors, 0 warnings")}`);
+              findings: [],
-      return;
+              errorCount: 0,
-    }
+              warningCount: 0,
-
+              filesScanned: 0,
-    for (const finding of allFindings) {
+            }),
-      const prefix = finding.severity === "error" ? c.error("✗") : c.warn("⚠");
+            null,
-      const loc = finding.elementId ? ` ${c.accent(`[${finding.elementId}]`)}` : "";
+            2,
-      console.log(
+          ),
-        `${prefix}  ${c.bold(finding.code)}${loc}: ${finding.message} ${c.dim(finding.file)}`,
+        );
-      );
+        process.exit(1);
-      if (finding.fixHint) {
-        console.log(`   ${c.dim(`Fix: ${finding.fixHint}`)}`);
       }
+      console.error(message);
+      process.exit(1);
     }
-
-    const summaryIcon = totalErrors > 0 ? c.error("◇") : c.success("◇");
-    console.log(`\n${summaryIcon}  ${totalErrors} error(s), ${totalWarnings} warning(s)`);
-    process.exit(totalErrors > 0 ? 1 : 0);
   },
 });