rebrand: MangaBM → BookmarkManager, add novel library support (#15)

Two intertwined changes — the rebrand and the novel library were developed on
the same branch because the novel UI plumbing is part of the new "Bookmark
Manager" wordmark in the web shell.

## What it does

- **Rebrand**: MangaBM → BookmarkManager across the Go module, compose stack,
  env vars, Traefik hostnames, container/image names, userscript storage
  prefixes (`mangabm:cache` → `bmgr:manga:cache`, `mangabm:queue` → `bmgr:manga:queue`),
  and docs.
- **Novel library**: same backend, two libraries. New `kind` column splits
  bookmarks into `manga` / `novel`; PUT validates it. Two userscripts:
  - `manga-bookmark.user.js` — unchanged behaviour, just stamps its own `kind`.
  - `novel-bookmark.user.js` — separate Violentmonkey install with adapters
    for **novelfull.com** (polled via headless browser — Cloudflare JS
    challenge) and **lightnovelworld.net** (polled via plain TLS).
- **Web UI**: library switch on the app shell. Login art, libswitch, and
  novel-site colours from the Cinder design snapshot.

## Plumbing

- `addedColumns` ALTER for `kind` runs on first start after upgrade; every
  pre-existing row is backfilled to `'manga'`. No manual SQL, no down-time.
- `ALLOWED_ORIGINS` gains the two novel sites.
- New `NOVEL_USERSCRIPT_PATH` env (default `/userscript/novel-bookmark.user.js`),
  bindmounted alongside the manga script.
- Traefik router names `mangabm*` → `bmapi*` / `bmweb*`.

## Test status

- `go test ./...` — green
- `node --test userscript/test/logic.test.js` — 34 pass
- `node --test userscript/test/novel-logic.test.js` — 11 pass
- `node --check` on both userscripts — clean

## Notes for the redeploy

.env keys were renamed (`MANGA_API_HOST` → `BOOKMARK_API_HOST`,
`MANGA_WEB_HOST` → `BOOKMARK_WEB_HOST`). Update DNS / Traefik labels on the
prod override before pulling, otherwise the public hostnames go dark.
See the redeploy instructions I'll post next to this PR.

Reviewed-on: #15
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>

backend/internal/web/templates/app.html

@@ -5,7 +5,7 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover">
   <meta name="color-scheme" content="dark light">
-  <title>mangaBookmark</title>
+  <title>BookmarkManager</title>
   <link rel="icon" href="/static/logo.svg" type="image/svg+xml">
   <link rel="stylesheet" href="/static/style.css">
   <link rel="preload" href="/static/fonts/instrument-serif-400-latin.woff2" as="font" type="font/woff2" crossorigin>
@@ -19,7 +19,15 @@
 {{template "icons" .}}
 <div class="sheet">
   <header class="topbar">
-    <h1 class="brand">{{template "mark" .}}<span>manga<em>Bookmark</em></span></h1>
+    <h1 class="brand">{{template "mark" .}}<span>Bookmark<em>Manager</em></span></h1>
+    {{/* Plain full-page links, not htmx swaps: switching library replaces the
+         tab row and the chrome, which is a page, not a fragment. */}}
+    <nav class="libswitch" aria-label="Library">
+      <a href="/?tab=all" class="{{if eq .Lib "manga"}}active{{end}}"
+         {{if eq .Lib "manga"}}aria-current="page"{{end}}>Manga</a>
+      <a href="/?lib=novel&amp;tab=all" class="{{if eq .Lib "novel"}}active{{end}}"
+         {{if eq .Lib "novel"}}aria-current="page"{{end}}>Novels</a>
+    </nav>
     <form method="post" action="/logout">
       <button type="submit" class="ghost">Log out</button>
     </form>
@@ -38,27 +46,31 @@
        navigation, not an ARIA tablist — aria-current carries "which bucket am
        I in" without owing a tabpanel contract we do not implement. */}}
   <nav class="tabs" aria-label="Bookmark buckets">
-    <a href="/?tab=all" class="{{if eq .Tab "all"}}active{{end}}"
+    <a href="{{.PageURL "all"}}" class="{{if eq .Tab "all"}}active{{end}}"
        {{if eq .Tab "all"}}aria-current="page"{{end}}
-       hx-get="/ui/list?tab=all" hx-target="#list" hx-swap="innerHTML"
-       hx-push-url="/?tab=all" hx-on::after-request="setActiveTab(this)">All</a>
-    <a href="/?tab=new" class="tab-new {{if eq .Tab "new"}}active{{end}}"
+       hx-get="{{.ListURL "all"}}" hx-target="#list" hx-swap="innerHTML"
+       hx-push-url="{{.PageURL "all"}}" hx-on::after-request="setActiveTab(this)">All</a>
+    {{/* The one bucket novels do not have: without a poller-fed "what is out
+         that I have not read", the tab would only ever restate All. */}}
+    {{if eq .Lib "manga"}}
+    <a href="{{.PageURL "new"}}" class="tab-new {{if eq .Tab "new"}}active{{end}}"
        {{if eq .Tab "new"}}aria-current="page"{{end}}
-       hx-get="/ui/list?tab=new" hx-target="#list" hx-swap="innerHTML"
-       hx-push-url="/?tab=new" hx-on::after-request="setActiveTab(this)">Updated
+       hx-get="{{.ListURL "new"}}" hx-target="#list" hx-swap="innerHTML"
+       hx-push-url="{{.PageURL "new"}}" hx-on::after-request="setActiveTab(this)">Updated
       {{template "newcount" .}}</a>
-    <a href="/?tab=fav" class="{{if eq .Tab "fav"}}active{{end}}"
+    {{end}}
+    <a href="{{.PageURL "fav"}}" class="{{if eq .Tab "fav"}}active{{end}}"
        {{if eq .Tab "fav"}}aria-current="page"{{end}}
-       hx-get="/ui/list?tab=fav" hx-target="#list" hx-swap="innerHTML"
-       hx-push-url="/?tab=fav" hx-on::after-request="setActiveTab(this)">Favourites</a>
-    <a href="/?tab=archived" class="{{if eq .Tab "archived"}}active{{end}}"
+       hx-get="{{.ListURL "fav"}}" hx-target="#list" hx-swap="innerHTML"
+       hx-push-url="{{.PageURL "fav"}}" hx-on::after-request="setActiveTab(this)">Favourites</a>
+    <a href="{{.PageURL "archived"}}" class="{{if eq .Tab "archived"}}active{{end}}"
        {{if eq .Tab "archived"}}aria-current="page"{{end}}
-       hx-get="/ui/list?tab=archived" hx-target="#list" hx-swap="innerHTML"
-       hx-push-url="/?tab=archived" hx-on::after-request="setActiveTab(this)">Archived</a>
-    <a href="/?tab=finished" class="{{if eq .Tab "finished"}}active{{end}}"
+       hx-get="{{.ListURL "archived"}}" hx-target="#list" hx-swap="innerHTML"
+       hx-push-url="{{.PageURL "archived"}}" hx-on::after-request="setActiveTab(this)">Archived</a>
+    <a href="{{.PageURL "finished"}}" class="{{if eq .Tab "finished"}}active{{end}}"
        {{if eq .Tab "finished"}}aria-current="page"{{end}}
-       hx-get="/ui/list?tab=finished" hx-target="#list" hx-swap="innerHTML"
-       hx-push-url="/?tab=finished" hx-on::after-request="setActiveTab(this)">Finished</a>
+       hx-get="{{.ListURL "finished"}}" hx-target="#list" hx-swap="innerHTML"
+       hx-push-url="{{.PageURL "finished"}}" hx-on::after-request="setActiveTab(this)">Finished</a>
   </nav>
   </div>