build: commit PDFium binaries directly instead of fetching in CI

The fetch-pdfium.sh + gitignore approach caused a silent file-loss
between the fetch step and tauri-action's cargo build on CI: the
fetch step logged `installed to .../src-tauri/pdfium:` with the
file present, but tauri-build.rs then reported "resource path
doesn't exist" / "Library not found". Locally reproduced by
removing the dylib — same error — confirming the file really is
missing at build.rs time on CI. Root cause never nailed down;
suspected interaction between .gitignore rules and something in
the CI pipeline cleaning gitignored files.

Pragmatic fix: just ship the three platform binaries in the repo
(~21 MB total). Pros:
- Eliminates the entire fetch/placement failure mode.
- CI builds don't depend on upstream release availability.
- Works the same way locally and in CI.

Cons (acknowledged):
- Repo size grows by ~21 MB.
- PDFium updates now require manual re-download + commit.

PDFium is licensed Apache 2.0 / BSD, redistribution is fine.

Removes:
- scripts/fetch-pdfium.sh
- "Fetch PDFium dynamic library" step in build.yml
- pdfium_platform matrix var
- .gitignore entries for *.dylib/*.dll/*.so under src-tauri/pdfium/
- src-tauri/pdfium/.gitkeep (no longer needed, dir has real content)

Author: nashsu

.github/workflows/build.yml

@@ -18,15 +18,12 @@ jobs:
           - platform: macos-latest
             args: '--target aarch64-apple-darwin'
             rust_target: aarch64-apple-darwin
-            pdfium_platform: mac-arm64
           - platform: ubuntu-22.04
             args: ''
             rust_target: ''
-            pdfium_platform: linux-x64
           - platform: windows-latest
             args: ''
             rust_target: ''
-            pdfium_platform: win-x64
 
     runs-on: ${{ matrix.platform }}
 
@@ -61,10 +58,6 @@ jobs:
       - name: Install frontend dependencies
         run: npm install
 
-      - name: Fetch PDFium dynamic library (${{ matrix.pdfium_platform }})
-        shell: bash
-        run: ./scripts/fetch-pdfium.sh ${{ matrix.pdfium_platform }}
-
       - name: Build Tauri app
         uses: tauri-apps/tauri-action@v0
         env:

.gitignore

@@ -11,12 +11,6 @@ src-tauri/target/
 # Tauri generated files
 src-tauri/gen/
 
-# Bundled PDFium binaries — downloaded per-platform by scripts/fetch-pdfium.sh
-# (invoked by CI). Too large to track in git.
-src-tauri/pdfium/*.dylib
-src-tauri/pdfium/*.dll
-src-tauri/pdfium/*.so
-
 # Environment files
 .env
 .env.local