Initial build: stash server + browser extension

Server (Express + better-sqlite3 + FTS5, mirroring keep's stack):
/api/capture (upsert-on-url, per PROPOSAL.md's dedup decision),
/api/articles (list/search/mark-read/delete), plus a minimal
server-rendered reading list and reader view at / and /read/:id
(token passed as ?t= there since browser navigation can't set an
Authorization header). Bearer-token auth generated via `npm run
token` — no login flow, matching keep's one-time identity
registration pattern.

Extension (Manifest V3, sideloaded, no store distribution): toolbar
click or context menu "Send to stash" runs @mozilla/readability
(vendored into extension/lib/) against the current page, falling back
to raw rendered HTML when extraction comes back too thin. Options
page for one-time server URL + token entry.

Verified end-to-end with the real extension loaded in a live Chromium
instance (not just unit-tested extraction logic): capture against a
real page, dedup-on-recapture, mark-read, FTS5 search, 401 on missing
auth, and both server-rendered views all confirmed working.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

extension/options.js

@@ -0,0 +1,17 @@
+const serverUrlEl = document.getElementById('serverUrl');
+const tokenEl = document.getElementById('token');
+const statusEl = document.getElementById('status');
+
+chrome.storage.local.get(['serverUrl', 'token']).then(({ serverUrl, token }) => {
+  if (serverUrl) serverUrlEl.value = serverUrl;
+  if (token) tokenEl.value = token;
+});
+
+document.getElementById('save').addEventListener('click', async () => {
+  await chrome.storage.local.set({
+    serverUrl: serverUrlEl.value.trim(),
+    token: tokenEl.value.trim(),
+  });
+  statusEl.textContent = 'Saved.';
+  setTimeout(() => { statusEl.textContent = ''; }, 2000);
+});