feat(aliases): add 3 minimal MCP testing aliases for convenience

## Summary

Add exactly 3 minimal bash aliases to make MCP protocol testing convenient without going overboard.

## Background

We've validated MCP protocol smoke tests but they require long JSON-RPC commands. Need convenient aliases for daily use while keeping them minimal.

## Proposed Aliases

Add to `.bash_aliases.mcp`:

### 1. `mcp-test` - Full handshake smoke test
```bash
alias mcp-test='(echo "{\"jsonrpc\": \"2.0\", \"id\": 1, \"method\": \"initialize\", \"params\": {\"protocolVersion\": \"2024-11-05\", \"capabilities\": {}, \"clientInfo\": {\"name\": \"smoke-test\", \"version\": \"1.0.0\"}}}"; echo "{\"jsonrpc\": \"2.0\", \"method\": \"notifications/initialized\"}"; echo "{\"jsonrpc\": \"2.0\", \"id\": 2, \"method\": \"tools/list\"}")'
```

### 2. `mcp-init` - Just initialization step
```bash
alias mcp-init='echo "{\"jsonrpc\": \"2.0\", \"id\": 1, \"method\": \"initialize\", \"params\": {\"protocolVersion\": \"2024-11-05\", \"capabilities\": {}, \"clientInfo\": {\"name\": \"test\", \"version\": \"1.0.0\"}}}"'
```

### 3. `mcp-tools` - Just tools/list (for debugging)
```bash
alias mcp-tools='echo "{\"jsonrpc\": \"2.0\", \"id\": 2, \"method\": \"tools/list\"}"'
```

## Usage Examples

```bash
# Full smoke test
mcp-test | .venv/bin/python -m mcp_server_git -r .

# Test just initialization
mcp-init | .venv/bin/python -m mcp_server_git -r .

# Test tools list (after proper handshake)
(mcp-init; echo '{"jsonrpc": "2.0", "method": "notifications/initialized"}'; mcp-tools) | .venv/bin/python -m mcp_server_git -r .
```

## Implementation

- Add to modular alias system: `.bash_aliases.mcp`
- Keep exactly 3 aliases - no more
- Focus on testing convenience, not comprehensive tooling

## Acceptance Criteria

- [ ] Create `.bash_aliases.mcp` with exactly 3 aliases
- [ ] Aliases work with existing MCP servers
- [ ] Update setup.sh to source the new alias file
- [ ] Document usage in MCP README

Keeps testing convenient without alias bloat.

Start with the existing modular alias setup and inspect setup.sh to see how alias files are sourced. Add exactly three aliases to .bash_aliases.mcp, update setup.sh, and document the provided usage examples in the MCP README. Done means the file contains only the three requested aliases and the acceptance criteria are met.

Written by the indexing model from the issue text.