chore(assets): jieba 词典 gzip 化 + 删未压缩 models-dev 目录（-7.4MB） (#22)

Two zero-cost APK size wins (~7.4MB) found by benchmarking against
taixu / OmniBot (docs/analysis-apk-size-vs-taixu-omnibot.md):

- models-dev-api.json (4.1MB): the app reads the .gzip copy first and
  the plaintext file was only a gunzip-failure fallback — for a local
  asset that means a corrupt APK, and the network refresh is the real
  fallback. Asset, code fallback branch, and the update script's
  plaintext output all removed. The catalog guard test now verifies the
  gzip itself is readable and still carries the known-majority
  providers instead of diffing two copies.
- jieba dictionaries (5.4MB → 2.1MB): jieba.dict.utf8 and hmm_model
  are now gzipped in assets and gunzipped onto filesDir at extract
  time; the native side keeps reading the plain file names, so
  jieba_jni.cpp is untouched. DICT_VERSION stays at 1 — content is
  unchanged and already-extracted copies remain valid.

Co-authored-by: tall-1997 <278631348+tall-1997@users.noreply.github.com>

Author: tall-1997

scripts/update_models_dev.sh

@@ -6,10 +6,11 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 IOS_DEST="$SCRIPT_DIR/../src/ios/Resources/models-dev-api.json"
-ANDROID_DEST="$SCRIPT_DIR/../src/android/app/src/main/assets/models-dev-api.json"
-# Android's asset merger strips the .gz suffix and would collide with the
-# plaintext fallback. Use .gzip so both assets can coexist in the APK.
-ANDROID_GZ="${ANDROID_DEST}.gzip"
+# [T-apk-size] Android ships ONLY the gzipped catalog (~416KB vs 4.1MB
+# plaintext). The plaintext copy used to sit next to it as a fallback, but
+# the app reads the gzip first and a local asset failing to gunzip means a
+# corrupt APK — the network path is the real fallback.
+ANDROID_GZ="$SCRIPT_DIR/../src/android/app/src/main/assets/models-dev-api.json.gzip"
 URL="https://models.dev/api.json"
 
 echo "Downloading $URL ..."