feat(sites): add bilibili dynamic support (images and animated images)

Fetch `t.bilibili.com/<id>`, `www.bilibili.com/opus/<id>`,
`t.bilibili.com/h5/dynamic/detail/<id>` and `m.bilibili.com/dynamic/<id>`
through the anonymous `/x/polymer/web-dynamic/v1/detail` endpoint (no
cookie, no WBI signature; the site adds the device cookies
`/x/frontend/finger/spi` hands out, which is what lifts bilibili's
`-352` risk control).

Media: the `major.draw` grid (`.gif` sources become animations, the rest
photos with a downscaled `@518w.jpg` thumbnail used both as preview and
as the oversized fallback), an attached video's cover, and the quoted
dynamic's media for forwards. The video stream itself is not resolved;
`b23.tv` short links stay unmatched (they mostly point at videos, so
matching them would turn a silently ignored link into a failure reply).

`-352`/`-412` map to a retryable error so the queue backs off instead of
dropping the post; a removed dynamic (`500`) is permanent.

Registry-driven, so no bot-side code changes beyond the site lists in the
command replies; found while researching nazurin and
telegram-bili-feed-helper (see BILIBILI_PLAN.md).

crates/x-media/src/site/bilibili/model.rs

@@ -0,0 +1,124 @@
+//! Serde DTOs for the Bilibili dynamic detail endpoint
+//! (`/x/polymer/web-dynamic/v1/detail`), mirroring live responses
+//! (field paths verified 2026-09-17). Every field is optional so an API
+//! shape change degrades to "no media" instead of a parse failure.
+
+use serde::Deserialize;
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Detail {
+    /// Business code: `0` = OK, `-352`/`-412` = risk control, `500`/`4101147`
+    /// = gone.
+    pub(crate) code: i64,
+    #[serde(default)]
+    pub(crate) message: Option<String>,
+    #[serde(default)]
+    pub(crate) data: Option<Data>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Data {
+    #[serde(default)]
+    pub(crate) item: Option<Box<Item>>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Item {
+    /// The dynamic id, same numeric id as in the URL.
+    #[serde(default)]
+    pub(crate) id_str: String,
+    #[serde(default)]
+    pub(crate) modules: Option<Modules>,
+    /// The quoted dynamic when this item is a forward. A forward shell often
+    /// carries no media of its own — the original holds it.
+    #[serde(default)]
+    pub(crate) orig: Option<Box<Item>>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Modules {
+    #[serde(default)]
+    pub(crate) module_author: Option<Author>,
+    #[serde(default)]
+    pub(crate) module_dynamic: Option<Dynamic>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Author {
+    #[serde(default)]
+    pub(crate) name: String,
+    #[serde(default)]
+    pub(crate) mid: Option<i64>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Dynamic {
+    #[serde(default)]
+    pub(crate) desc: Option<Desc>,
+    #[serde(default)]
+    pub(crate) major: Option<Major>,
+    /// A single topic (`{"id":…,"name":…}`), the dynamic's only tag source.
+    #[serde(default)]
+    pub(crate) topic: Option<Topic>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Desc {
+    #[serde(default)]
+    pub(crate) text: String,
+}
+
+/// `major` is a tagged union: `type` (`MAJOR_TYPE_DRAW` / `_ARCHIVE` / …)
+/// plus one payload object per type. Only the two payloads this adapter reads
+/// are modeled; an unknown major simply yields no media.
+#[derive(Deserialize, Debug)]
+pub(crate) struct Major {
+    #[serde(default)]
+    pub(crate) draw: Option<Draw>,
+    #[serde(default)]
+    pub(crate) archive: Option<Archive>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Draw {
+    #[serde(default)]
+    pub(crate) items: Vec<Pic>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Pic {
+    /// Image URL, served as `http://` — normalized to https by the adapter.
+    pub(crate) src: String,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Archive {
+    /// The attached video's cover — the only image an AV dynamic has (the
+    /// video itself is deliberately not resolved, see the module docs).
+    #[serde(default)]
+    pub(crate) cover: Option<String>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct Topic {
+    #[serde(default)]
+    pub(crate) name: String,
+}
+
+/// Response of the anonymous fingerprint endpoint (`/x/frontend/finger/spi`),
+/// the source of the adapter's device cookies.
+#[derive(Deserialize, Debug)]
+pub(crate) struct Fingerprint {
+    #[serde(default)]
+    pub(crate) data: Option<FingerprintData>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct FingerprintData {
+    /// Sent as the `buvid3` cookie.
+    #[serde(default, rename = "b_3")]
+    pub(crate) buvid3: String,
+    /// Sent as the `buvid4` cookie.
+    #[serde(default, rename = "b_4")]
+    pub(crate) buvid4: String,
+}