fix(layout): fix the wrong prop name for getting all the `_data` items which belong to `wiki`

[wangziling]

1. fix(layout): fix the wrong prop name for getting all the _data items which belong to wiki

It seems that currently the prop name changed to tree. 看起来好像属性名从以前的 projects 变成了 tree。

hexo: 7.2.0
hexo-cli: 4.3.2
os: win32 10.0.22631 undefined
node: 20.12.2
acorn: 8.11.3
ada: 2.7.6
ares: 1.27.0
base64: 0.5.2
brotli: 1.1.0
cjs_module_lexer: 1.2.2
cldr: 44.1
icu: 74.2
llhttp: 8.1.2
modules: 115
napi: 9
nghttp2: 1.60.0
nghttp3: 0.7.0
ngtcp2: 0.8.1
openssl: 3.0.13+quic
simdutf: 4.0.8
tz: 2024a
undici: 5.28.4
unicode: 15.1
uv: 1.46.0
uvwasi: 0.0.20
v8: 11.3.244.8-node.19
zlib: 1.3.0.1-motley-40e35a7

2. fix(layout): fix the issue that always shows only one tag for wiki index page
3. Create .gitignore to ignore the changes when current repo being as a submodule