feat(web): Nightjar web app - Plaud-style record/transcribe/summarise UI

A runnable, self-hosted web interface so the whole workflow can be tested end to
end: record or upload audio in the browser, watch it transcribe and summarise,
browse a library, play back, and export.

What changed:
- server/app/store.py: SQLite + on-disk audio storage for recordings (stdlib only).
- server/app/pipeline.py: background task audio -> transcribe -> summarise via the
  existing provider layer, updating status (queued/transcribing/summarising/done/error).
- server/app/main.py: web API - POST upload, list, detail, audio (Range), delete, and
  export (txt/md/srt/vtt/json) - and serves the SPA at /.
- server/app/web/: Plaud-style single-page UI (index.html, styles.css, app.js). Sidebar
  library, in-browser recording (MediaRecorder) + file upload, live status polling,
  audio player, summary (overview/key points/actions), timestamped transcript, exports.
- server/Dockerfile + README: two-minute run instructions (default provider: Groq free
  tier for both Whisper + LLM), and a Docker option.
- config: env prefix switched OPENSCRIBE_ -> NIGHTJAR_ to match the brand and the site
  tutorials; .env.example rewritten with a ready Groq quick-start.
- state/TODO: web app recorded as done.

Why:
- User asked for a Plaud-like web interface to test how it all works. Nothing testable
  existed before (marketing site is a brochure; pipeline was unwired). This delivers a
  real, runnable product demo and effectively lands M5/M6 for the HTTP providers.

Notes:
- Slim by design: AI is offloaded to the configured provider, so no local ML deps needed
  for the demo. Byte-compiles clean; JS passes node --check. Local faster-whisper still
  needs its model (M5) for the fully-offline path.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/app/web/styles.css

@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-3.0-only  -  Nightjar web UI */
+:root{
+  --ink:#0e1116; --panel:#161b22; --panel2:#1c2230; --line:#2a3140; --text:#e8edf4;
+  --muted:#93a0b4; --accent:#e0894e; --accent2:#5fc7bf; --ok:#3fb950; --bad:#f85149;
+  --sans:ui-sans-serif,system-ui,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
+  --mono:ui-monospace,"Cascadia Code",Consolas,monospace;
+}
+*{box-sizing:border-box} html,body{height:100%}
+body{margin:0;font-family:var(--sans);color:var(--text);background:var(--ink);}
+.topbar{display:flex;align-items:center;justify-content:space-between;height:56px;padding:0 18px;border-bottom:1px solid var(--line);background:rgba(14,17,22,.8);backdrop-filter:blur(8px);position:sticky;top:0;z-index:5}
+.brand{font-weight:800;letter-spacing:.3px;display:flex;align-items:center;gap:10px}
+.brand .dot{width:12px;height:12px;border-radius:50%;background:radial-gradient(circle at 40% 40%,var(--accent2),transparent 70%),var(--accent);box-shadow:0 0 12px rgba(95,199,191,.6)}
+.providers{font-family:var(--mono);font-size:.72rem;color:var(--muted)}
+.layout{display:grid;grid-template-columns:320px 1fr;height:calc(100vh - 56px)}
+.sidebar{border-right:1px solid var(--line);display:flex;flex-direction:column;min-height:0;background:var(--panel)}
+.actions{display:flex;gap:8px;padding:14px}
+.btn{cursor:pointer;border:1px solid var(--line);background:var(--panel2);color:var(--text);border-radius:10px;padding:9px 14px;font-weight:600;font-size:.92rem;text-align:center;flex:1;transition:.14s}
+.btn:hover{border-color:var(--accent)}
+.btn.primary{background:linear-gradient(135deg,var(--accent),#d1783c);border:none;color:#14100a}
+.btn.recording{background:var(--bad);color:#fff;animation:pulse 1.4s infinite}
+@keyframes pulse{50%{opacity:.6}}
+.rec-timer{padding:0 14px 8px;color:var(--bad);font-family:var(--mono);font-size:.8rem}
+.list{list-style:none;margin:0;padding:6px;overflow-y:auto;flex:1}
+.item{padding:11px 12px;border-radius:10px;cursor:pointer;border:1px solid transparent}
+.item:hover{background:var(--panel2)}
+.item.sel{background:var(--panel2);border-color:var(--accent)}
+.item .t{font-weight:600;font-size:.94rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
+.item .m{display:flex;gap:8px;align-items:center;margin-top:3px;color:var(--muted);font-size:.76rem}
+.badge{font-size:.68rem;padding:1px 7px;border-radius:999px;border:1px solid var(--line);font-family:var(--mono)}
+.badge.done{color:var(--ok);border-color:#2ea04355}
+.badge.error{color:var(--bad);border-color:#f8514955}
+.badge.proc{color:var(--accent2);border-color:#5fc7bf55}
+.detail{overflow-y:auto;padding:26px 30px}
+.empty{max-width:460px;margin:12vh auto 0;text-align:center;color:var(--muted)}
+.empty h2{color:var(--text)}
+.head h1{margin:0 0 4px;font-size:1.5rem}
+.head .sub{color:var(--muted);font-size:.85rem;display:flex;gap:10px;align-items:center;margin-bottom:16px}
+audio{width:100%;margin:6px 0 20px}
+.card{background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:18px 20px;margin-bottom:18px}
+.card h3{margin:0 0 10px;font-size:1.05rem}
+.card ul{margin:6px 0 0;padding-left:18px;color:#d7deea}
+.card li{margin:4px 0}
+.overview{color:#d7deea;line-height:1.6}
+.seg{display:flex;gap:12px;padding:6px 0;border-bottom:1px solid #1f2733}
+.seg .ts{font-family:var(--mono);color:var(--accent2);font-size:.78rem;min-width:64px;padding-top:2px}
+.seg .tx{color:#cdd6e2;line-height:1.5}
+.exports{display:flex;flex-wrap:wrap;gap:8px;margin-top:6px}
+.exports a{font-size:.82rem;text-decoration:none;color:var(--text);border:1px solid var(--line);border-radius:8px;padding:6px 11px}
+.exports a:hover{border-color:var(--accent)}
+.spinner{display:inline-block;width:14px;height:14px;border:2px solid var(--line);border-top-color:var(--accent2);border-radius:50%;animation:spin .8s linear infinite;vertical-align:-2px}
+@keyframes spin{to{transform:rotate(360deg)}}
+.right{margin-left:auto}
+.link-danger{color:var(--bad);cursor:pointer;font-size:.82rem;background:none;border:none}
+@media(max-width:720px){.layout{grid-template-columns:1fr}.sidebar{display:none}}