Enhance user configuration management and logging

- Introduced user configuration command to set API key.
- Updated README and documentation for user config and logging paths.
- Refactored logging to support user-specific log files.
- Added tests for user configuration and logging behavior.

docs/PACKAGING_DISTRIBUTION.md

@@ -0,0 +1,187 @@
+# Python Internal Distribution Guide
+
+This document describes how to distribute `nexus-claude-api` internally without publishing to PyPI.
+
+## Recommended Options
+
+Use one of these two approaches:
+
+- **Wheel distribution**: build a `.whl` file and send it to colleagues. This is best for stable internal releases.
+- **Private Git installation**: let colleagues install directly from the company Git repository. This is best for teammates who can access the source code or need frequent updates.
+
+Both options require:
+
+- Python `>=3.11`
+- Access to PyPI or the company Python package mirror for runtime dependencies
+- A personal AI Nexus API key
+
+Do not share `nexus-claude-api.local.json`, `.env`, logs, or any personal API key.
+
+## Option 1: Build and Share a Wheel
+
+A wheel is the standard Python install package format. It is not an `.exe`; colleagues install it with `pip`, then run the installed `nexus-claude-api` command.
+
+### Publisher Steps
+
+1. Confirm the package version in `pyproject.toml`:
+
+   ```toml
+   [project]
+   name = "nexus-claude-api"
+   version = "0.1.0"
+   ```
+
+   Update the version for every released package. Avoid sending different builds with the same version.
+
+2. Run the supported checks:
+
+   ```powershell
+   uv sync --extra dev
+   uv run pytest
+   uv run nexus-claude-api start --dry-run
+   ```
+
+3. Build the package:
+
+   ```powershell
+   uv build
+   ```
+
+   This creates files under `dist/`, usually:
+
+   ```text
+   dist/nexus_claude_api-0.1.0-py3-none-any.whl
+   dist/nexus_claude_api-0.1.0.tar.gz
+   ```
+
+4. Test the wheel in a clean environment:
+
+   ```powershell
+   py -3.11 -m venv C:\Temp\nexus-claude-api-test
+   C:\Temp\nexus-claude-api-test\Scripts\python.exe -m pip install .\dist\nexus_claude_api-0.1.0-py3-none-any.whl
+   C:\Temp\nexus-claude-api-test\Scripts\nexus-claude-api.exe start --dry-run
+   ```
+
+5. Send only the `.whl` file to colleagues through an approved internal channel.
+
+### Colleague Installation
+
+Install the wheel:
+
+```powershell
+py -3.11 -m pip install .\nexus_claude_api-0.1.0-py3-none-any.whl
+```
+
+Configure the personal Nexus key:
+
+```powershell
+nexus-claude-api config set --api-key "your-nexus-api-key"
+```
+
+Start the local proxy and print the Claude Code helper:
+
+```powershell
+nexus-claude-api start --port 4141 --claude-code
+```
+
+If PowerShell cannot find the installed script, use the module form:
+
+```powershell
+py -3.11 -m nexus_claude_api start --port 4141 --claude-code
+```
+
+### Upgrade
+
+Send a new wheel with a new version, then ask colleagues to run:
+
+```powershell
+py -3.11 -m pip install --upgrade .\nexus_claude_api-0.1.1-py3-none-any.whl
+```
+
+## Option 2: Install from Private Git
+
+Private Git installation avoids manual wheel sharing. It still uses the Python package metadata from `pyproject.toml`, so the installed command is the same.
+
+### Publisher Steps
+
+1. Push the code to the company Git repository.
+
+2. Update the version in `pyproject.toml` for each released version.
+
+3. Tag stable versions:
+
+   ```powershell
+   git tag v0.1.0
+   git push origin v0.1.0
+   ```
+
+   For the next release:
+
+   ```powershell
+   git tag v0.1.1
+   git push origin v0.1.1
+   ```
+
+4. Share an install command that points to a tag:
+
+   ```powershell
+   py -3.11 -m pip install "git+https://company-git.example.com/group/nexus-claude-api.git@v0.1.0"
+   ```
+
+Prefer tags or exact commit SHAs. Avoid asking normal users to install from `main`, because repeated installs can produce different code over time.
+
+### Colleague Installation
+
+Install from the company Git repository:
+
+```powershell
+py -3.11 -m pip install "git+https://company-git.example.com/group/nexus-claude-api.git@v0.1.0"
+```
+
+Configure the personal Nexus key:
+
+```powershell
+nexus-claude-api config set --api-key "your-nexus-api-key"
+```
+
+Start the local proxy:
+
+```powershell
+nexus-claude-api start --port 4141 --claude-code
+```
+
+### Upgrade
+
+Upgrade to a newer tag:
+
+```powershell
+py -3.11 -m pip install --upgrade "git+https://company-git.example.com/group/nexus-claude-api.git@v0.1.1"
+```
+
+### Development Clone
+
+For colleagues who will modify or test the source code:
+
+```powershell
+git clone https://company-git.example.com/group/nexus-claude-api.git
+cd nexus-claude-api
+uv sync --extra dev
+uv run nexus-claude-api start --dry-run
+```
+
+## Choosing Between the Two
+
+- Use **wheel distribution** for normal internal users who only need a stable tool.
+- Use **private Git installation** for colleagues who understand the repository, need fast updates, or help develop the project.
+- Keep version numbers and Git tags aligned. For example, `pyproject.toml` version `0.1.0` should correspond to tag `v0.1.0`.
+
+## Release Checklist
+
+Before sharing a release:
+
+- Run `uv run pytest`.
+- Run `uv run nexus-claude-api start --dry-run`.
+- Test wheel installation in a clean Python environment.
+- If using Git installation, test install from the exact tag.
+- Confirm no personal credentials are included.
+- Confirm `nexus-claude-api.local.json`, `.env`, logs, caches, and `dist/` artifacts are not committed accidentally.