⚡ Bolt: Batch MCP OAuth token fetches to fix N+1 query

[Donach]

💡 What: Implemented getTokensForServers in UserMCPOAuthTokenRepository and updated injectPerUserOAuthTokens hook to batch load tokens and map them via an in-memory Map using compound keys.
🎯 Why: Solved an N+1 query problem where the FeathersJS hook fetched OAuth tokens iteratively inside a Promise.all loop for each MCP server in the result.
📊 Impact: Reduces database queries from O(N) to O(1) (2 batched queries) during MCP server list retrieval.
🔬 Measurement: Check the database logs during a request to /session-mcp-servers or /mcp-servers with a list of servers to ensure only two SELECT statements are executed for tokens rather than one for each server.

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PR created automatically by Jules for task 2233015174498339841 started by @Donach

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