fix(cli): move LeetCode fetches to GraphQL and restore history from the profile

LeetCode's REST /api/* endpoints now answer a Cloudflare 403 to non-browser
clients, which broke the picker's problem index on an empty cache. The index
and descriptions now come from /graphql, and test/submit fold the signed-in
profile's submission history into the solutions table once a day, so a lost
db or a fresh clone recovers both orderings.

apps/cli/solutions.ts

@@ -9,7 +9,9 @@
  *
  * Every run backfills the db's solutions table with created_at (from the
  * file's birthtime, mtime when the filesystem has none) so ordering works for
- * files that predate the db. Files git reports as modified, added or
+ * files that predate the db, and at most once a day folds in the signed-in
+ * LeetCode profile's submission history (see db.ts), which survives a lost db
+ * or a fresh clone. Files git reports as modified, added or
  * untracked come first, newest edit first — the problem being worked on is
  * the focused option, so Enter runs it without a search. The rest are ordered
  * per command — test lists the most recently tested first (never-tested
@@ -19,10 +21,10 @@
  * Library: side-effect-free on import — nothing scans the filesystem until
  * runOnSolution() is called.
  */
-import { autocomplete, cancel, isCancel, log } from "@clack/prompts";
+import { autocomplete, cancel, isCancel, log, spinner } from "@clack/prompts";
 import { statSync } from "node:fs";
 import { basename, join, relative } from "node:path";
-import { problemDb } from "./db";
+import { fetchSubmissions, leetcodeCredentials, problemDb } from "./db";
 import { ROOT, WORK as WORK_DIR, parseWorkPath } from "./work";
 
 /** Leading LC number of a work/ file, or undefined for unnumbered names. */
@@ -77,6 +79,36 @@ export async function runOnSolution(
       new Date(stat.birthtimeMs || stat.mtimeMs).toISOString(),
     );
   }
+
+  // the profile's history: first and latest submission per work/ problem
+  if (db.historyStale()) {
+    const auth = leetcodeCredentials();
+    if (!auth) {
+      log.warn("Not signed in to leetcode-cli — run `leetcode login` to restore history from your profile.");
+    } else {
+      const s = spinner();
+      s.start("Syncing submission history from your LeetCode profile");
+      try {
+        const bySlug = new Map<string, number>();
+        for (const f of scanned) {
+          const parsed = parseWorkPath(f);
+          if (parsed) bySlug.set(parsed.slug, parsed.lc);
+        }
+        const history = new Map<number, { first: string; last: string }>();
+        for (const { slug, at } of await fetchSubmissions(auth)) {
+          const id = bySlug.get(slug);
+          if (id === undefined) continue;
+          const seen = history.get(id);
+          if (!seen) history.set(id, { first: at, last: at });
+          else if (at < seen.first) seen.first = at;
+          else if (at > seen.last) seen.last = at;
+        }
+        s.stop(`Synced submission history for ${db.foldHistory(history)} solutions`);
+      } catch (err) {
+        s.error(`Submission history sync failed (${err}) — using cached timestamps`);
+      }
+    }
+  }
   const activity = db.solutionActivity();
 
   // test → most recently tested first; submit → most recently created first