perf: P0/P1/P2 low-latency and maintainability improvements

P0:
- blockhash/nonce: get_transaction_blockhash returns Result; buy/sell entry validation
- Bonk sell: remove RPC get_token_balance from build path; require caller to pass input_amount
- Hot path: drop redundant dex_type/protocol_params clone; tip via sol_f64_to_lamports (no String)
- compute_budget cache uses Arc; extend_compute_budget_instructions avoids SmallVec clone

P1:
- middleware protocol_name takes &str; executor destructures result once to avoid signatures/submit_timings clone
- Error messages include dex context; params use Copy for Pubkey; pumpswap utils clone only Pool for pools[0]

P2:
- transaction_pool capacity constants; TIP_ACCOUNT_CACHE marked allow(dead_code)
- Fix error copy in raydium_amm_v4 / meteora_damm_v2 to correct protocol names

Made-with: Cursor

src/constants/swqos.rs

@@ -242,6 +242,7 @@ pub const SWQOS_ENDPOINTS_FLASHBLOCK: [&str; 8] = [
 ];
 
 /// BlockRazor Send Transaction v2: plain-text Base64 body, auth in URI, Content-Type: text/plain. Keep-alive: POST /v2/health.
+/// 若 HTTP 返回 500，可尝试 HTTPS：https://<region>.solana.blockrazor.io/v2/sendTransaction（Frankfurt/NewYork/Tokyo），通过 custom_url 覆盖。
 pub const SWQOS_ENDPOINTS_BLOCKRAZOR: [&str; 8] = [
     "http://newyork.solana.blockrazor.xyz:443/v2/sendTransaction",
     "http://frankfurt.solana.blockrazor.xyz:443/v2/sendTransaction",