docs: Production deployment guide - includes macOS launchd, not just Linux

## Problem

The deployment docs are Linux-only. macOS users get:

> "Some distributions of Linux do not support this tool; consult their documentation for configuration instructions."

That's it. No launchd plist example, no macOS-specific gotchas.

## What's missing

### macOS/launchd (completely undocumented)
- No launchd plist example
- No guidance on KeepAlive, RunAtLoad, graceful shutdown
- No mention of where to put data/logs on macOS

### Durability (buried in a 2023 blog post)
- `dolt_transaction_commit` is critical for durability but not explained in server docs
- No explanation of what survives ungraceful shutdown vs graceful
- The config.yaml template shows it commented out with no warning

### Crash recovery
- What to do after SIGKILL/OOM/power loss?
- How to verify database integrity?
- Any fsck equivalent?

## Real-world impact

I ran `dolt sql-server` on macOS for 13 days without launchd management. After an ungraceful restart, data was lost because:
1. No launchd = no graceful SIGTERM on logout/restart
2. `dolt_transaction_commit` wasn't enabled (I didn't know it mattered
3. No docs told me either of these things

## Suggested additions

1. **macOS launchd plist example** alongside the systemd unit
2. **Durability section** explaining and when fsync actually happens
3. **Production checklist** with recommended settings for both platforms

## Working launchd plist (for reference)

Here's what I ended up creating manually:

And the critical config.yaml setting:

EOF
)

Start by reading the existing Linux deployment docs and systemd unit, then compare the requested macOS launchd plist, durability guidance, crash-recovery steps, and production checklist against the server documentation and config.yaml template. Done means the documentation covers both platforms, explains dolt_transaction_commit and shutdown behavior, and gives macOS-specific paths and recovery guidance.

Written by the indexing model from the issue text.