Remove conda installation instructions and promote uv as primary method

[Copilot]

The conda-forge package is outdated (0.24.2 vs PyPI 0.25.3) and maintaining it adds overhead for a pure Python package. This PR removes conda installation methods and promotes uv as the recommended installer.

Changes

README.md

• Removed Anaconda badge and conda installation section
• Added uv as recommended method (before pip)
• Added migration note for conda users with removal instructions

openpiv/docs/src/installation_instruction.rst

• Removed Anaconda from dependencies and installation sections
• Added uv section with rationale (speed, reliability)
• Added warning box with migration instructions for conda users

Installation hierarchy

### Recommended: Using uv (fastest)
pip install uv
uv pip install openpiv

### Using pip (standard)
pip install openpiv

### Note on Conda/Anaconda
⚠️ Conda packages are no longer actively maintained

pip remains available as the standard fallback method.

Original prompt

Objective

Modernize the installation documentation by removing outdated conda/anaconda installation methods and promoting modern Python package installation tools (uv and pip).

Background

The conda-forge package for OpenPIV is behind the PyPI version (conda-forge: 0.24.2, PyPI: 0.25.3). Maintaining conda packages adds significant overhead with minimal benefit for a pure Python package. The Python packaging ecosystem has evolved, and tools like uv provide faster, more reliable installation.

Tasks

1. Remove Conda/Anaconda Installation Instructions

File: README.md

• Remove the line: conda install -c openpiv openpiv
• Remove the Anaconda badge: ![Anaconda](https://anaconda.org/openpiv/openpiv/badges/version.svg)
• Remove the ## Or 'conda' section entirely

File: openpiv/docs/src/installation_instruction.rst

• Remove the conda installation command: conda install -c alexlib openpiv
• Remove references to Anaconda in the dependencies section
• Remove the recommendation for Anaconda as a Python distribution

2. Add uv as the Recommended Installation Method

File: README.md

• Add a new section promoting uv as the fastest, recommended method
• Include clear installation instructions for uv
• Position this BEFORE the pip installation section

Example structure:

## Installing

### Recommended: Using uv (fastest)

[uv](https://github.com/astral-sh/uv) is a fast Python package installer and resolver written in Rust:

    pip install uv
    uv pip install openpiv

### Using pip (standard)

Use PyPI: <https://pypi.python.org/pypi/OpenPIV>:

    pip install openpiv

File: openpiv/docs/src/installation_instruction.rst

• Add a new section for uv installation with proper reStructuredText formatting
• Include a brief explanation of why uv is recommended (speed, reliability)
• Provide clear installation steps

3. Keep pip as Standard Fallback

Both files:

• Ensure pip installation instructions remain clear and accessible
• Keep pip as the "standard" or "traditional" method
• Maintain the PyPI link and badge

4. Remove the Anaconda Badge

File: README.md

• Remove this line completely: ![Anaconda](https://anaconda.org/openpiv/openpiv/badges/version.svg)
• Keep the PyPI badge: ![PyPI](https://img.shields.io/pypi/v/openpiv)

5. Add Migration Note for Existing Conda Users

File: README.md

• Add a new section (perhaps titled "Note on Conda/Anaconda" or "Migrating from Conda")
• Explain that conda packages are no longer actively maintained
• Provide migration instructions

Example:

### Note on Conda/Anaconda

⚠️ **Conda packages are no longer actively maintained.** The conda-forge package may be outdated.

If you previously installed OpenPIV via conda, you can migrate to pip or uv:

    # Remove the conda package
    conda remove openpiv
    
    # Install with pip or uv
    pip install openpiv
    # or
    uv pip install openpiv

File: openpiv/docs/src/installation_instruction.rst

• Add a similar note in reStructuredText format
• Include in a prominent location (perhaps a warning/note box)

Expected Outcome

After this PR:

• Users will see uv as the recommended, modern installation method
• pip remains available as the standard fallback
• No conda/anaconda references remain in installation instructions
• Existing conda users have clear migration instructions
• The README and documentation are cleaner and more maintainable

Files to Modify

• README.md
• openpiv/docs/src/installation_instruction.rst

Testing

• Verify all markdown and reStructuredText formatting renders correctly
• Check that all links are valid
• Ensure the documentation builds without errors

This pull request was created from Copilot chat.

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