fix(submit): make the draft chain survive continuous writing, reloads and flaky networks

Autosave only ran after 4s of idle, and every keystroke reset that timer, so a
writer who never stopped had zero saves (measured: 15s of typing = 0 requests).
Saving also never rebound the URL, so a new draft could not be found again after
a reload, the local backup was cleared on every autosave, and a failed save had
no retry and stayed failed once the network came back.

Client
- autosave: keep the idle debounce but add a 30s max-wait window that is not
  reset by further keystrokes, and retry failures at 5s / 15s / 60s
- bind `?edit=<id>` into the URL once the server returns a post id, so reloads,
  new tabs and history all reopen the same draft
- only clear the local backup when the save settled and nothing changed since
- key the local backup by draft id instead of the constant `jio-studio-0`
- restore snapshots through hydrateBlocks so code blocks come back editable
- never disable publish while an autosave is in flight, and mark autosave
  states separately (自动保存中… / 已自动保存 / 自动保存失败，将重试)
- on 409, adopt the server rev and tell the author instead of failing silently
- status bar reports the real save state instead of a bogus Markdown hint

Server
- draft saves no longer rewrite the lifecycle: pending / future / publish /
  private posts keep their status, so an autosave cannot pull a submitted post
  out of the review queue
- drafts and autosaves stop consuming the publish flood quota, which is meant to
  cap actual publishing (measured: 4 drafts used to burn 4 slots)
- autosave skips wp_save_post_revision for both plain drafts and submission
  versions; manual saves and submits still create a revision to roll back to
- media-only drafts (image / table / code / hr) count as content
- the response now carries the resulting status so the client can tell
  "just submitted" from "still under review"

Tests cover the max-wait window, retry schedule, URL binding, backup clearing,
status labelling and every server-side draft rule.

src/Core/SubmissionVersion.php

@@ -192,7 +192,7 @@ final class SubmissionVersion {
 	/**
 	 * 创建或更新作者的工作版本。
 	 *
-	 * @param array{title?:string,content?:string,excerpt?:string,snapshot?:array<string,mixed>,base_rev?:int} $data
+	 * @param array{title?:string,content?:string,excerpt?:string,snapshot?:array<string,mixed>,base_rev?:int,autosave?:bool} $data
 	 * @return array{success:bool,message?:string,version_id?:int,rev?:int,conflict?:bool}|\WP_Error
 	 */
 	public function save_working(int $source_id, int $user_id, array $data, bool $submit = false) {
@@ -265,7 +265,16 @@ final class SubmissionVersion {
 			'post_excerpt' => $excerpt,
 			'post_status'  => $next_status === self::STATUS_PENDING ? 'pending' : 'draft',
 		];
+		// 自动保存不建 revision：几秒一次地写版本表会把改稿记录撑满，
+		// 需要回滚的节点由手动保存与提交产生。
+		$is_auto = !empty($data['autosave']);
+		if ($is_auto) {
+			remove_action('post_updated', 'wp_save_post_revision');
+		}
 		$updated = wp_update_post($update, true);
+		if ($is_auto) {
+			add_action('post_updated', 'wp_save_post_revision');
+		}
 		if (is_wp_error($updated)) {
 			return new \WP_Error('jio_version_failed', $updated->get_error_message(), ['status' => 500]);
 		}