fix(updater): emit .sig + latest.json in CI bundle + correct repo URL

The v0.1.0 draft release built successfully but only shipped the .dmg
and .app.tar.gz — the .app.tar.gz.sig signature and latest.json
manifest were missing, so the auto-updater couldn't verify any future
download. Two root causes:

* tauri.conf.json::bundle — Tauri 2 requires an explicit
  `createUpdaterArtifacts: true` flag to register the .sig + manifest
  as bundle outputs that tauri-action will then upload. The older
  Tauri 1 trick of adding `"updater"` to `targets` is no longer
  honored. With the flag missing, the .sig was generated as a side
  effect of TAURI_SIGNING_PRIVATE_KEY but never made it into the
  upload list.

* tauri.conf.json::plugins.updater.endpoints — pointed at
  `https://github.com/hsng95/lumen-rs/...` (personal handle), but the
  repo actually lives at `https://github.com/rabbitson87/lumen-rs/...`
  (the GitHub account). Auto-updater would have hit a 404 on every
  check even if the manifest had been generated.

Also corrected:
* README.md — "Install from a release" link now points at the right
  GitHub repo.
* crates/lumen-app/docs/release.md — sample latest.json URL.

(The `hsng95/lumen-rs-fixtures` references in DEPENDENCIES.md /
getting-started.md / maintainer-workflow.md are intentional — that's
the HuggingFace dataset repo, which is a separate org/handle from the
GitHub repo.)

v0.1.0 draft + tag wiped (both local and remote) before this commit
so the next tag push triggers a fresh build with all artifacts.

Author: rabbitson87

README.md

@@ -90,7 +90,7 @@ reads, and self-updates from GitHub Releases.
 
 ### Install from a release
 
-1. Open the [latest GitHub Release](https://github.com/hsng95/lumen-rs/releases/latest).
+1. Open the [latest GitHub Release](https://github.com/rabbitson87/lumen-rs/releases/latest).
 2. Download the `aarch64` `.dmg`. **Apple Silicon only** — MLX is
    ARM64-native and refuses to build on x86_64, so there is no Intel
    Mac bundle.

crates/lumen-app/docs/release.md

@@ -98,7 +98,7 @@ GitHub Releases pattern (referenced by `tauri.conf.json::plugins.updater.endpoin
   "platforms": {
     "darwin-aarch64": {
       "signature": "<contents of Lumen.app.tar.gz.sig>",
-      "url": "https://github.com/hsng95/lumen-rs/releases/download/v0.2.0/Lumen_0.2.0_aarch64.app.tar.gz"
+      "url": "https://github.com/rabbitson87/lumen-rs/releases/download/v0.2.0/Lumen_0.2.0_aarch64.app.tar.gz"
     }
   }
 }

crates/lumen-app/tauri.conf.json

@@ -30,6 +30,7 @@
   "bundle": {
     "active": true,
     "targets": ["app", "dmg"],
+    "createUpdaterArtifacts": true,
     "icon": [],
     "category": "DeveloperTool",
     "shortDescription": "Local LLM control plane",
@@ -47,7 +48,7 @@
       "active": true,
       "dialog": false,
       "endpoints": [
-        "https://github.com/hsng95/lumen-rs/releases/latest/download/latest.json"
+        "https://github.com/rabbitson87/lumen-rs/releases/latest/download/latest.json"
       ],
       "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IEJEOEIyRUFEQzVBODE1N0UKUldSK0ZhakZyUzZMdmFpdGdWSDlBQkhiaHZHYVJnaXpoUnFlNzFWalZKSEtSZFpFdnBhV29ZbEkK"
     }