feat: Improve DiskANN cross-platform compatibility and add Arch Linux support (#66)

* feat: Enhance CLI with improved list and smart remove commands

## ✨ New Features

### 🏠 Enhanced `leann list` command
- **Better UX**: Current project shown first with clear separation
- **Visual improvements**: Icons (🏠/📂), better formatting, size info
- **Smart guidance**: Context-aware usage examples and getting started tips

### 🛡️ Smart `leann remove` command
- **Safety first**: Always shows ALL matching indexes across projects
- **Intelligent handling**:
  - Single match: Clear location display with cross-project warnings
  - Multiple matches: Interactive selection with final confirmation
- **Prevents accidents**: No more deleting wrong indexes due to name conflicts
- **User-friendly**: 'c' to cancel, clear visual hierarchy, detailed info

### 🔧 Technical improvements
- **Clean logging**: Hide debug messages for better CLI experience
- **Comprehensive search**: Always scan all projects for transparency
- **Error handling**: Graceful handling of edge cases and user input

## 🎯 Impact
- **Safer**: Eliminates risk of accidental index deletion
- **Clearer**: Users always know what they're operating on
- **Smarter**: Automatic detection and handling of common scenarios

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

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

* chore: vscode ruff, and format

* fix: Update DiskANN submodule with MKL linking improvements

Updates DiskANN submodule to include fix for MKL linking issues:
- Replaces global link_libraries() with target-specific linking
- Uses dynamic MKL linking (mkl_rt) for better cross-platform compatibility
- Prevents MKL contamination of unrelated targets (like zlib tests)
- Resolves build failures on strict linkers (Arch Linux) while maintaining Ubuntu compatibility

DiskANN commit: c593831 - fix: Replace global MKL linking with target-specific approach

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

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

* chore: all linux deps

* fix: Update Intel MKL download link to avoid 403 error

- Replace problematic Intel download URL that returns 403 Forbidden
- Use general Intel oneAPI MKL page instead of specific download parameters
- This fixes the lychee link checker CI failure

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

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

* fix: Configure lychee to use browser User-Agent for Intel links

- Replace domain exclusion with browser User-Agent to properly check Intel links
- Intel website blocks automated tools but allows browser-like requests
- This enables proper link validation while avoiding 403 Forbidden errors

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

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

* fix: Use curl User-Agent for lychee link checking

Intel website has specific anti-bot logic:
- Blocks browser User-Agents (returns 403)
- Blocks lychee default User-Agent (returns 403)
- Allows curl User-Agent (returns 200)

This enables proper link validation for Intel documentation.

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

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

README.md

@@ -87,17 +87,60 @@ git submodule update --init --recursive
 ```
 
 **macOS:**
+
+Note: DiskANN requires MacOS 13.3 or later.
+
 ```bash
-brew install llvm libomp boost protobuf zeromq pkgconf
-CC=$(brew --prefix llvm)/bin/clang CXX=$(brew --prefix llvm)/bin/clang++ uv sync
+brew install libomp boost protobuf zeromq pkgconf
+uv sync --extra diskann
 ```
 
-**Linux:**
-```bash
-# Ubuntu/Debian (For Arch Linux: sudo pacman -S blas lapack openblas libaio boost protobuf abseil-cpp zeromq)
-sudo apt-get update && sudo apt-get install -y libomp-dev libboost-all-dev protobuf-compiler libabsl-dev libmkl-full-dev libaio-dev libzmq3-dev
+**Linux (Ubuntu/Debian):**
 
-uv sync
+Note: On Ubuntu 20.04, you may need to build a newer Abseil and pin Protobuf (e.g., v3.20.x) for building DiskANN. See [Issue #30](https://github.com/yichuan-w/LEANN/issues/30) for a step-by-step note.
+
+You can manually install [Intel oneAPI MKL](https://www.intel.com/content/www/us/en/developer/tools/oneapi/onemkl.html) instead of `libmkl-full-dev` for DiskANN. You can also use `libopenblas-dev` for building HNSW only, by removing `--extra diskann` in the command below.
+
+```bash
+sudo apt-get update && sudo apt-get install -y \
+  libomp-dev libboost-all-dev protobuf-compiler libzmq3-dev \
+  pkg-config libabsl-dev libaio-dev libprotobuf-dev \
+  libmkl-full-dev
+
+uv sync --extra diskann
+```
+
+**Linux (Arch Linux):**
+
+```bash
+sudo pacman -Syu && sudo pacman -S --needed base-devel cmake pkgconf git gcc \
+  boost boost-libs protobuf abseil-cpp libaio zeromq
+
+# For MKL in DiskANN
+sudo pacman -S --needed base-devel git
+git clone https://aur.archlinux.org/paru-bin.git
+cd paru-bin && makepkg -si
+paru -S intel-oneapi-mkl intel-oneapi-compiler
+source /opt/intel/oneapi/setvars.sh
+
+uv sync --extra diskann
+```
+
+**Linux (RHEL / CentOS Stream / Oracle / Rocky / AlmaLinux):**
+
+See [Issue #50](https://github.com/yichuan-w/LEANN/issues/50) for more details.
+
+```bash
+sudo dnf groupinstall -y "Development Tools"
+sudo dnf install -y libomp-devel boost-devel protobuf-compiler protobuf-devel \
+  abseil-cpp-devel libaio-devel zeromq-devel pkgconf-pkg-config
+
+# For MKL in DiskANN
+sudo dnf install -y intel-oneapi-mkl intel-oneapi-mkl-devel \
+  intel-oneapi-openmp || sudo dnf install -y intel-oneapi-compiler
+source /opt/intel/oneapi/setvars.sh
+
+uv sync --extra diskann
 ```
 
 </details>