jackett: its config dir is placed, and its tools find their own key

The manifest named /services/jackett/config and /var/lib/mesh/jackett/config.json — host
paths ADR 0112 takes out of definitions. The config dir is now a pathless directory
(${dir:config}) and the runtime's config and route binding live in a placed state dir, as
searxng does.

The image is pinned to v0.24.2627-ls34, the digest ace runs today; the old pin
(v0.24.2517-ls16) was older than the running version.

The runtime reached jackett at a fixed 127.0.0.1:9117; it now uses ${port:9117}, the
machine port the mesh actually assigned.

The tools never loaded: the client needed an API key nobody set. Like sonarr/radarr read
config.xml, it now reads APIKey from Jackett's own ServerConfig.json (the config dir is
already mounted read-only), so no secret goes into an assignment. jackett_indexers called
/api/v2.0/indexers, which is the web UI's endpoint and answers an API key with a redirect;
it now reads the Torznab t=indexers feed, and treats Torznab's 200-with-<error> as a
failure.

Verified: catalogue key tests (MESH_CATALOGUE set, not skipped); a throwaway container of
the pinned image on a fresh 0700 1000:1000 config dir serves its UI; the client discovers
the key from the generated ServerConfig.json, lists 617 indexers through the Torznab feed,
searches via /results, and a wrong key is refused; client.ts typechecks under --strict.

modules/jackett/tools/index.ts

@@ -9,7 +9,7 @@ export function getJackettTools(jackett: JackettClient): ToolDefinition[] {
   return [
     {
       name: "jackett_indexers",
-      description: "List the indexers Jackett proxies, with their type and any last error.",
+      description: "List the indexers Jackett proxies, with their type and site.",
       input: { all: { type: "boolean", description: "include indexers not yet configured (default false)" } },
       run: async (args) => {
         const indexers = await jackett.getIndexers(!args.all);