Update documentation and roadmap

[weter11]

Updated the project documentation across README.md (root and SteamFlow/), TODO.md, and ROADMAP.md. These updates reflect the current state of the SteamFlow implementation, including the integration of Steam Cloud Sync, PICS metadata fetching, and improved Proton support. Also cleaned up a leftover merge conflict marker in the subfolder README.

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PR created automatically by Jules for task 11068053059498982070 started by @weter11

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