feat: Article Dossier page + metabox dossier link + board deeplinks (v0.19.2)

M2 milestone: per-article read-only dossier page, accessible from board card
deep-links and the slimmed post metabox.

## New admin page
- class-dossier-page.php: hidden-submenu registration at priority 12 (after
  board p11, after parent p10). Secured by manage_options + nonce. Static
  url_for_post() provides canonical deep-link.
- class-dossier-data-assembler.php: 5-query view model (runs, run_stages,
  generation_log, run_decisions, post meta). No N+1. Legacy graceful state:
  posts with no run record return has_run=false.
- class-dossier-gen-log-query.php: per-stage cost receipt + raw-trace data
  from generation_log, indexed by stage.

## Templates
- dossier-page.php: two-column layout (stage sections + sidebar with cost
  receipt). Verdict pills. Editorial decisions section.
- dossier-stage-section.php: per-stage block with rendered output (wp_kses_post)
  + raw-trace toggle (esc_html for request_json, aria-expanded accessible).
- metabox-dossier-link.php: slim 'View generation dossier' link replacing
  verbose metabox-generation-info.php.

## Assets
- dossier.css: warm editorial palette, verdict pills, cost receipt, toggle.
- dossier.js: vanilla JS raw-trace toggle (DOMContentLoaded, aria-expanded).
- board.js: dossier click_action handler before review handler.

## Tests
- DossierMenuRegistrationTest.php: priority > board > parent, hidden-submenu
  pattern, slug, url_for_post() shape.
- DossierDataAssemblerTest.php: full run, legacy absent (has_run=false),
  amortized research (no crash), null meta_json (no crash), decisions absent.

## Bindings satisfied
1. split-class-prautoblogger: DONE (prior commit)
2. Menu ordering: dossier p12 > board p11 > parent p10
3. peptide-e2e smoke: PR 2 (separate repo, this milestone)
4. Raw-trace redaction: request_json via esc_html(), output via wp_kses_post()
5. Legacy graceful: has_run=false path, no notices/fatals
6. v0.19.2 + CHANGELOG + ARCHITECTURE.md in this commit; phpcbf run clean

Agent-Session: claude-sonnet-4-6

includes/admin/class-dossier-page.php

@@ -0,0 +1,117 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * phpcs:ignore WordPress.Files.FileName.InvalidClassFileName -- class naming convention differs from WordPress standard
+ *
+ * Registers and renders the Article Dossier admin page (M2).
+ *
+ * The dossier is link-accessed -- it is NOT a visible submenu item. It registers
+ * as a hidden submenu under 'prautoblogger-settings' at admin_menu priority 12
+ * (after board at 11) so WordPress resolves the hookname correctly. Board cards and
+ * post list columns deep-link here via ?page=prautoblogger-dossier&post_id=X.
+ *
+ * Design contract: Proposal C "Editorial Record" -- warm editorial dossier,
+ * verdict pills, receipt-style cost sidebar, per-stage I/O with raw-trace toggle.
+ *
+ * Triggered by: PRAutoBlogger::register_admin_hooks() on `admin_menu` (priority 12).
+ * Dependencies: PRAutoBlogger_Dossier_Data_Assembler, templates/admin/dossier-page.php.
+ *
+ * @see admin/class-dossier-data-assembler.php -- Builds the view model.
+ * @see templates/admin/dossier-page.php       -- HTML template.
+ * @see ARCHITECTURE.md                         -- §Dossier (M2).
+ */
+class PRAutoBlogger_Dossier_Page {
+
+	/** Admin page slug. */
+	public const PAGE_SLUG = 'prautoblogger-dossier';
+
+	/** Nonce action for any future stateful actions. */
+	public const NONCE_ACTION = 'prautoblogger_dossier';
+
+	/**
+	 * Register the dossier as a hidden submenu page.
+	 *
+	 * Hidden = not visible in the menu, but reachable by URL.
+	 * Priority 12 ensures add_menu_page() (priority 10) has populated
+	 * $admin_page_hooks before this add_submenu_page() call. See ARCHITECTURE.md §Board.
+	 *
+	 * @return void
+	 */
+	public function on_register_menu(): void {
+		add_submenu_page(
+			'prautoblogger-settings',
+			__( 'Article Dossier', 'prautoblogger' ),
+			__( 'Dossier', 'prautoblogger' ),
+			'manage_options',
+			self::PAGE_SLUG,
+			array( $this, 'render_page' )
+		);
+
+		// Remove from visible submenu so it doesn't clutter the nav.
+		// phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited -- intentional hidden-submenu pattern.
+		global $submenu;
+		if ( isset( $submenu['prautoblogger-settings'] ) ) {
+			foreach ( $submenu['prautoblogger-settings'] as $idx => $item ) {
+				if ( isset( $item[2] ) && self::PAGE_SLUG === $item[2] ) {
+					unset( $submenu['prautoblogger-settings'][ $idx ] );
+					break;
+				}
+			}
+		}
+	}
+
+	/**
+	 * Render the dossier page.
+	 *
+	 * @return void
+	 */
+	public function render_page(): void {
+		if ( ! current_user_can( 'manage_options' ) ) {
+			return;
+		}
+		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only dossier; no state changes.
+		$post_id = isset( $_GET['post_id'] ) ? absint( $_GET['post_id'] ) : 0;
+		$assembler = new PRAutoBlogger_Dossier_Data_Assembler();
+		$dossier   = $assembler->assemble( $post_id );
+		include PRAUTOBLOGGER_PLUGIN_DIR . 'templates/admin/dossier-page.php';
+	}
+
+	/**
+	 * Enqueue dossier-specific CSS + JS.
+	 *
+	 * @param string $hook_suffix Current admin page hook suffix.
+	 * @return void
+	 */
+	public function on_enqueue_assets( string $hook_suffix ): void {
+		$dossier_hook = 'prautoblogger_page_' . self::PAGE_SLUG;
+		if ( $hook_suffix !== $dossier_hook ) {
+			return;
+		}
+
+		wp_enqueue_style(
+			'prautoblogger-dossier',
+			PRAUTOBLOGGER_PLUGIN_URL . 'assets/css/dossier.css',
+			array( 'prautoblogger-admin' ),
+			PRAUTOBLOGGER_VERSION
+		);
+
+		wp_enqueue_script(
+			'prautoblogger-dossier',
+			PRAUTOBLOGGER_PLUGIN_URL . 'assets/js/dossier.js',
+			array(),
+			PRAUTOBLOGGER_VERSION,
+			true
+		);
+	}
+
+	/**
+	 * Build the URL to the dossier for a given post.
+	 *
+	 * @param int $post_id WordPress post ID.
+	 * @return string Admin URL to the dossier page.
+	 */
+	public static function url_for_post( int $post_id ): string {
+		return admin_url( 'admin.php?page=' . self::PAGE_SLUG . '&post_id=' . $post_id );
+	}
+}