feat(L04): add Git status add and commit card

doc/assets/git-three-states.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">Trzy stany Git</title><desc id="desc">Plik roboczy przechodzi przez git add do indeksu, a git commit zapisuje snapshot i przesuwa gałąź.</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="25" y="55" width="145" height="90" rx="10"/><rect x="227" y="55" width="145" height="90" rx="10"/><rect x="430" y="55" width="145" height="90" rx="10"/></g><g font-family="system-ui,sans-serif" text-anchor="middle" fill="#16324a"><text x="97" y="90" font-size="17" font-weight="700">WORKTREE</text><text x="97" y="117" font-size="13">?? notes.txt</text><text x="299" y="90" font-size="17" font-weight="700">INDEX</text><text x="299" y="117" font-size="13">A  notes.txt</text><text x="502" y="90" font-size="17" font-weight="700">COMMIT</text><text x="502" y="117" font-size="13">snapshot + message</text></g><g stroke="#16324a" stroke-width="3" marker-end="url(#a)"><path d="M170 100H217"/><path d="M372 100H420"/></g><text x="195" y="87" font-family="system-ui,sans-serif" text-anchor="middle" font-size="12" fill="#b6402d">git add</text><text x="399" y="87" font-family="system-ui,sans-serif" text-anchor="middle" font-size="12" fill="#b6402d">git commit</text><text x="300" y="184" font-family="system-ui,sans-serif" text-anchor="middle" font-size="15" fill="#16324a">status pokazuje różnice między trzema stanami</text></svg>