feat: add BOB Gateway BTC offramp action provider

[nud3l]

Summary

• Adds a new bob-gateway action provider that enables swapping EVM tokens to native BTC via BOB Gateway
• Three actions: get_supported_routes (discover available tokens/chains), swap_to_btc (execute EVM-to-BTC swaps with balance checks, approval, and gateway registration), get_orders (check order status by ID or list all orders for the connected wallet)
• Includes a GatewayClient wrapping all BOB Gateway REST API endpoints with timeout, size limits, and route caching
• Dynamic source chain resolution from wallet network ID against the Gateway routes API
• Slippage in basis points (default 300 = 3%, max 1000 = 10%)

Notes

• The BTC recipient address is provided by the agent or user as an input parameter, since agentkit does not currently have BTC wallet support
• Once agentkit adds BTC wallet support, we'd like to extend this provider with BTC-to-EVM onramping as well

Test plan

• 44 unit tests covering action provider (22 tests) and gateway client (22 tests)
• Schema validation tests for BTC address formats, amount strings, slippage bounds, and order ID
• Error handling: insufficient balance, reverted transactions, registration failures, unsupported routes
• TypeScript compiles with zero errors
• Prettier formatting passes
• Rebased on latest main with no conflicts

🤖 Generated with Claude Code

[cb-heimdall]

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