refactor: Cleanup git state - commit all staged changes

Major refactoring cleanup:
- Add new controller architecture (class-controller-*.php)
- Add new settings-v2 UI (views/settings-v2/)
- Add new CSS architecture (agentic-sidebar.css, tokens)
- Add esbuild build pipeline (scripts/build.js, package.json)
- Add composer dependencies (vendor/)
- Add frontend src directory (assets/js/src/index.jsx)
- Add documentation files
- Remove old/obsolete files (class-settings.php, old CSS)

This commits all pending changes from previous refactoring efforts.

views/settings-v2/tab-cost-log.php

@@ -0,0 +1,66 @@
+<?php
+/**
+ * Settings V2: Cost Log.
+ *
+ * @package WP_Agentic_Writer
+ */
+
+if (!defined("ABSPATH")) {
+    exit();
+} ?>
+<div class="section-head"><div><p class="eyebrow"><?php esc_html_e(
+    "Spend visibility",
+    "wp-agentic-writer",
+); ?></p><h2><?php esc_html_e(
+    "OpenRouter cost log",
+    "wp-agentic-writer",
+); ?></h2><p><?php esc_html_e(
+    "Review usage, monthly spend, and per-post OpenRouter costs.",
+    "wp-agentic-writer",
+); ?></p></div><button type="button" class="btn btn-small" id="wpaw-export-csv"><?php esc_html_e(
+    "Export CSV",
+    "wp-agentic-writer",
+); ?></button></div>
+<div class="panel"><div class="panel-head"><div class="panel-title"><h3><?php esc_html_e(
+    "Monthly summary",
+    "wp-agentic-writer",
+); ?></h3><p><?php esc_html_e(
+    "Current month usage from the cost tracker.",
+    "wp-agentic-writer",
+); ?></p></div></div><div class="panel-body grid-3"><div class="metric-card"><div class="metric-value">$<?php echo esc_html(
+    number_format_i18n($monthly_used, 2),
+); ?></div><div class="metric-label"><?php esc_html_e(
+    "Used",
+    "wp-agentic-writer",
+); ?></div></div><div class="metric-card"><div class="metric-value">$<?php echo esc_html(
+    number_format_i18n($monthly_budget, 2),
+); ?></div><div class="metric-label"><?php esc_html_e(
+    "Budget",
+    "wp-agentic-writer",
+); ?></div></div><div class="metric-card"><div class="metric-value"><?php echo esc_html(
+    number_format_i18n($budget_percent, 1),
+); ?>%</div><div class="progress"><span style="width: <?php echo esc_attr(
+    min(100, $budget_percent),
+); ?>%"></span></div><div class="metric-label"><?php esc_html_e(
+    "Budget usage",
+    "wp-agentic-writer",
+); ?></div></div></div></div>
+<div class="panel"><div class="panel-head"><div class="panel-title"><h3><?php esc_html_e(
+    "Recent usage",
+    "wp-agentic-writer",
+); ?></h3><p><?php esc_html_e(
+    "Expand each post to see action-level calls and costs.",
+    "wp-agentic-writer",
+); ?></p></div></div><div class="panel-body"><table class="ds-table" id="wpaw-cost-log-table"><thead><tr><th><?php esc_html_e(
+    "Post",
+    "wp-agentic-writer",
+); ?></th><th><?php esc_html_e(
+    "Actions / calls",
+    "wp-agentic-writer",
+); ?></th><th><?php esc_html_e(
+    "Total cost",
+    "wp-agentic-writer",
+); ?></th></tr></thead><tbody id="wpaw-cost-log-tbody"><tr><td colspan="3"><?php esc_html_e(
+    "Cost data will appear after OpenRouter generations.",
+    "wp-agentic-writer",
+); ?></td></tr></tbody></table></div></div>