Add accounts, presets, live sheet panel and equipment tiles

- Login with registration code, sessions, rate limiting, per-user characters
- Share characters with other users (read-only), admin CLI
- Rules presets with a Presets tab, applied/pending changes with diff in a side sheet
- Equipment as tiles with amounts, starting kit removed
- Rename nav tab to "Character", add "New character" button
- Stop tracking _to_delete/

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HJhXuLD2Z6hv3Wqeq9UL9K

frontend/src/styles.css

@@ -147,3 +147,18 @@ ul.desclist { list-style: none; padding: 0; margin: 0 0 .5rem; display: grid; ga
 main { max-width: 1280px; }
 @media (max-width: 1100px) { .creator-body { grid-template-columns: minmax(0, 1fr) 360px; } }
 @media (max-width: 800px) { .creator-body { grid-template-columns: 1fr; } }
+tr.dim td { opacity: .55; }
+.skillcols { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 0 2rem; }
+.skillgroup h5 { margin: .8em 0 .2em; color: var(--diesium); font-size: .9rem; }
+
+.loginbox { margin-top: 3rem; }
+.loginbox form button[type="submit"] { margin-top: .5rem; }
+
+.sharepanel { margin-top: .8rem; padding-top: .6rem; border-top: 1px solid var(--line); }
+.sharepanel form input { flex: 1; }
+.chip button.linklike { color: inherit; text-decoration: none; margin-left: .2rem; }
+.top nav a.navchar { max-width: 22ch; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+
+.card.tile { display: flex; flex-direction: column; gap: .3rem; }
+.card.tile.on { border-color: var(--noxium); box-shadow: inset 0 0 0 1px var(--noxium); background: var(--panel2); }
+.tilestepper { margin-top: auto; padding-top: .4rem; justify-content: flex-end; }