Port to Go: 1:1 feature parity

[mrf]

Summary

Port the existing Rust implementation to Go with 1:1 feature parity. No new features, no architectural changes - just a straight port.

Motivation

• Faster iteration with Go's sub-second compile times
• Leverage existing Go expertise
• Foundation for future Bubble Tea improvements

Scope

Port all existing functionality:

Panels

• Meetings panel (macOS Calendar.app via osascript)
• PRs panel (gh CLI integration)
• Ports panel (lsof parsing)
• Git status panel (uncommitted work scanning)
• Stashes panel

Features

• Config file parsing (~/.config/dcc/config.toml)
• Keyboard shortcuts (q, r, p, m, g, Tab, Shift+Tab)
• Color coding (meeting buffer, PR age, stash age)
• Auto-refresh interval
• Panel focus/selection

Data Fetching

• osascript for Calendar events
• gh search prs for GitHub PRs
• lsof -i -P -n for ports
• git status --porcelain for repo status
• git stash list for stashes

Out of Scope

• Bubble Tea / Elm Architecture (separate issue)
• New panels (Jira, Claude sessions)
• Windows support
• Architectural improvements

Technical Notes

Use basic Go TUI approach initially:

• github.com/gdamore/tcell/v2 or raw terminal handling
• Simple event loop matching current Rust structure
• Direct port of current architecture

Acceptance Criteria

• All panels render identically to Rust version
• All keyboard shortcuts work
• Config file compatible with existing format
• go build produces working binary