feat(L02): add tmux sessions and panes card

doc/assets/tmux-model.svg

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+<svg xmlns="http://www.w3.org/2000/svg" width="600" height="210" viewBox="0 0 600 210" role="img" aria-labelledby="title desc"><title id="title">Model tmux</title><desc id="desc">Klienci łączą się z serwerem, który utrzymuje sesje zawierające okna i panele.</desc><defs><marker id="a" markerWidth="9" markerHeight="9" refX="8" refY="3" orient="auto"><path d="M0 0L0 6L8 3z" fill="#16324a"/></marker></defs><rect width="600" height="210" fill="#f7fafc"/><g fill="#eef3f7" stroke="#16324a" stroke-width="2"><rect x="20" y="55" width="110" height="90" rx="10"/><rect x="170" y="55" width="110" height="90" rx="10"/><rect x="320" y="55" width="110" height="90" rx="10"/><rect x="470" y="55" width="110" height="90" rx="10"/></g><g font-family="system-ui,sans-serif" text-anchor="middle" fill="#16324a"><text x="75" y="90" font-size="17" font-weight="700">CLIENT</text><text x="75" y="117" font-size="13">attach/detach</text><text x="225" y="90" font-size="17" font-weight="700">SERVER</text><text x="225" y="117" font-size="13">socket</text><text x="375" y="90" font-size="17" font-weight="700">SESSION</text><text x="375" y="117" font-size="13">windows</text><text x="525" y="90" font-size="17" font-weight="700">WINDOW</text><text x="525" y="117" font-size="13">panes</text></g><g stroke="#16324a" stroke-width="3" marker-end="url(#a)"><path d="M130 100H160"/><path d="M280 100H310"/><path d="M430 100H460"/></g><text x="300" y="184" font-family="system-ui,sans-serif" text-anchor="middle" font-size="15" fill="#b6402d">detach zamyka klienta — serwer i procesy pozostają</text></svg>