refactor: purge Node.js, Rust is the one true backend

- Moved boosapi-rs/* to repo root
- Deleted all Node.js source (src/server/, src/web/, scripts/)
- Deleted node_modules, package.json, tsconfig, vite.config
- Updated .gitignore and AGENTS.md for Rust-only stack
- Fixed static file path for frontend dist/web/
- Dockerfile stays the same (already Rust-only)
- Kept dist/web/ for Rust static serving

.gitignore

@@ -1,35 +1,20 @@
+/target
+**/*.rs.bk
+Cargo.lock
+.env
+.env.*
+data/
 node_modules/
 dist/
 release/
-data/*
-!data/.gitkeep
-.env
 *.log
-*.tar.gz
 logs/
-tmp/*
+tmp/
 !tmp/.gitkeep
-.worktrees/
-
-# Local desktop/debug artifacts
-/.tmp-*
-/main.js
-/NUL
-/.playwright-cli/
-
 .DS_Store
 Thumbs.db
 docker/data/
 docker/.env
-
-# Local planning docs
-docs/plan/
-docs/plans/
 .ace-tool/
-
-# Local ComfyUI development install
 .comfyui/
-
-# Rust binary
 boosapi
-boosapi-rs/target/