✨ Split init and auth wiring (#258)

Why: make setup and auth commands dependable before the API, server, and client integration slices land on top. These commands are first-run and account-boundary surfaces, so they need clear behavior, isolated state, and tests that exercise user-visible outcomes.\n\nWhat changed:\n- Tightened init config generation and plugin loading behavior.\n- Hardened login/logout/whoami auth flows with injectable boundaries and clearer failure handling.\n- Added focused command tests for init, login, logout, whoami, config, and context behavior.\n- Kept CLI test runs isolated from real local auth/config state.\n\nVerification:\n- npm run lint\n- npm run build\n- node --test tests/commands/init.test.js tests/commands/login.test.js tests/commands/logout.test.js tests/commands/whoami.test.js\n- GitHub CI: CI Status, Node 22, Node 24, SDK E2E, SDK Unit Status, and GitHub visual workflows all passed.\n\nNote: external Vizzly CLI Reporter requested review for a recurring mobile fullscreen-viewer visual diff outside this PR's code scope.

Author: Robdel12

src/commands/config-cmd.js

@@ -2,6 +2,7 @@
  * Config command - query and display configuration
  */
 
+import { CONFIG_DEFAULTS } from '../config/core.js';
 import { loadConfig as defaultLoadConfig } from '../utils/config-loader.js';
 import * as defaultOutput from '../utils/output.js';
 
@@ -40,10 +41,10 @@ export async function configCommand(
 
     // Build the config object to display
     let displayConfig = {
-      server: config.server || { port: 47392, timeout: 30000 },
+      server: config.server || CONFIG_DEFAULTS.server,
       build: config.build || {},
       upload: config.upload || {},
-      comparison: config.comparison || { threshold: 2.0 },
+      comparison: config.comparison || CONFIG_DEFAULTS.comparison,
       tdd: config.tdd || {},
     };
 

src/commands/context.js

@@ -29,7 +29,7 @@ function validateLimitRange(value, flagName, { min = 1, max }) {
   }
 
   if (!Number.isInteger(value) || value < min || value > max) {
-    return [`${flagName} must be a number between ${min} and ${max}`];
+    return [`${flagName} must be an integer between ${min} and ${max}`];
   }
 
   return [];
@@ -41,7 +41,7 @@ function validateOffset(value) {
   }
 
   if (!Number.isInteger(value) || value < 0) {
-    return ['--offset must be a non-negative number'];
+    return ['--offset must be a non-negative integer'];
   }
 
   return [];