Remove PDF from git tracking and update project metadata

- Remove pulse_core_1_technical_report.pdf from git tracking (should be generated locally)
- Update DOI in README.md citation (10.57967/hf/6605)
- Update paper/.gitignore to exclude markdown files
- PDF files should be generated locally from LaTeX source, not tracked in git

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -262,7 +262,7 @@ If you use this model, please cite:
     title        = { Pulse Core 1 - Vietnamese Text Classification Model },
     year         = 2025,
     url          = { https://huggingface.co/undertheseanlp/pulse_core_1 },
-    doi          = { 10.57967/hf/6599 },
+    doi          = { 10.57967/hf/6605 },
     publisher    = { Hugging Face }
 }
 ```

paper/.gitignore

@@ -1,5 +1,4 @@
 # Ignore all files except .pdf, .tex, and .md
 *
 !*.tex
-!*.md
 !.gitignore

paper/pulse_core_1_technical_report.pdf

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:1757066504213905c276030f610e0eeca77e132f90c5683f4f866c7530cb97a2
-size 242770