feature: add stats api

[OpenSteam001]

Summary

This PR adds optional Stats SteamID API support for stats and achievements.

Previously, when no Lua setStat(appid, "steamid") override was configured, OpenSteamTool always fell back to the hardcoded default SteamID. With this change, OpenSteamTool can now query the official stats API to obtain a recommended SteamID for the current AppId.

Behavior

The SteamID resolution priority is now:

1. Lua setStat(appid, "steamid")
2. Stats API, when [stats] enable_api = true and the API returns a valid SteamID
3. Hardcoded fallback SteamID 76561198028121353

This keeps existing Lua configurations fully compatible while improving the default behavior for games without a manually configured setStat.

New Configuration

[stats]
# Query the official stats API when no Lua setStat override exists.
# Priority: setStat > stats API > hardcoded preset SteamID.
enable_api = true

Users can set enable_api = false to disable the remote API lookup and keep the old fallback-only behavior.

Implementation Details

• Added StatsClient for querying the stats API.
• Added thread-safe in-memory caching to avoid repeated API requests for the same AppId.
• Added validation for API responses: only HTTP 200 responses containing a valid non-zero uint64 SteamID are accepted.
• Integrated the API lookup into LuaConfig::GetStatSteamId.
• Added [stats] enable_api parsing to the main config loader.
• Updated README.md, README_ES.md, and opensteamtool.example.toml.

Compatibility

Existing setStat() usage is not affected. Manually configured SteamIDs still have the highest priority.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid blocking stats packet sends on the API call

When an unlocked app has no setStat override and the stats API is enabled by default, this synchronous WinHTTP request runs inside LuaConfig::GetStatSteamId, which is called from the outgoing user-stats packet handlers before forwarding the packet. If stats.opensteamtool.com is slow or unreachable, each uncached app can stall Steam/game networking until the HTTP timeouts expire; failures are not cached, so the stall repeats on later stats requests. Consider resolving this asynchronously, prefetching, or caching failures/using much shorter configurable timeouts.

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