refactor: Reorganize src/ into modular folder structure

Split large monolithic files into focused modules:
- cloudcode-client.js (1,107 lines) → src/cloudcode/ (9 files)
- account-manager.js (639 lines) → src/account-manager/ (5 files)
- Move auth files to src/auth/ (oauth, token-extractor, database)
- Move CLI to src/cli/accounts.js

Update all import paths and documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/cloudcode/model-api.js

@@ -0,0 +1,97 @@
+/**
+ * Model API for Cloud Code
+ *
+ * Handles model listing and quota retrieval from the Cloud Code API.
+ */
+
+import { ANTIGRAVITY_ENDPOINT_FALLBACKS, ANTIGRAVITY_HEADERS } from '../constants.js';
+import { logger } from '../utils/logger.js';
+
+/**
+ * List available models in Anthropic API format
+ * Fetches models dynamically from the Cloud Code API
+ *
+ * @param {string} token - OAuth access token
+ * @returns {Promise<{object: string, data: Array<{id: string, object: string, created: number, owned_by: string, description: string}>}>} List of available models
+ */
+export async function listModels(token) {
+    const data = await fetchAvailableModels(token);
+    if (!data || !data.models) {
+        return { object: 'list', data: [] };
+    }
+
+    const modelList = Object.entries(data.models).map(([modelId, modelData]) => ({
+        id: modelId,
+        object: 'model',
+        created: Math.floor(Date.now() / 1000),
+        owned_by: 'anthropic',
+        description: modelData.displayName || modelId
+    }));
+
+    return {
+        object: 'list',
+        data: modelList
+    };
+}
+
+/**
+ * Fetch available models with quota info from Cloud Code API
+ * Returns model quotas including remaining fraction and reset time
+ *
+ * @param {string} token - OAuth access token
+ * @returns {Promise<Object>} Raw response from fetchAvailableModels API
+ */
+export async function fetchAvailableModels(token) {
+    const headers = {
+        'Authorization': `Bearer ${token}`,
+        'Content-Type': 'application/json',
+        ...ANTIGRAVITY_HEADERS
+    };
+
+    for (const endpoint of ANTIGRAVITY_ENDPOINT_FALLBACKS) {
+        try {
+            const url = `${endpoint}/v1internal:fetchAvailableModels`;
+            const response = await fetch(url, {
+                method: 'POST',
+                headers,
+                body: JSON.stringify({})
+            });
+
+            if (!response.ok) {
+                const errorText = await response.text();
+                logger.warn(`[CloudCode] fetchAvailableModels error at ${endpoint}: ${response.status}`);
+                continue;
+            }
+
+            return await response.json();
+        } catch (error) {
+            logger.warn(`[CloudCode] fetchAvailableModels failed at ${endpoint}:`, error.message);
+        }
+    }
+
+    throw new Error('Failed to fetch available models from all endpoints');
+}
+
+/**
+ * Get model quotas for an account
+ * Extracts quota info (remaining fraction and reset time) for each model
+ *
+ * @param {string} token - OAuth access token
+ * @returns {Promise<Object>} Map of modelId -> { remainingFraction, resetTime }
+ */
+export async function getModelQuotas(token) {
+    const data = await fetchAvailableModels(token);
+    if (!data || !data.models) return {};
+
+    const quotas = {};
+    for (const [modelId, modelData] of Object.entries(data.models)) {
+        if (modelData.quotaInfo) {
+            quotas[modelId] = {
+                remainingFraction: modelData.quotaInfo.remainingFraction ?? null,
+                resetTime: modelData.quotaInfo.resetTime ?? null
+            };
+        }
+    }
+
+    return quotas;
+}