⚡ Optimize batch insertion in bib_chips and RD data tables

[iwismer]

💡 What:

Optimized replace_bib_chips, replace_participants, replace_divisions, and replace_rd_data in services/receiver/src/db.rs by replacing single-row loop inserts with batch chunked INSERT OR REPLACE INTO ... VALUES statements (using a batch chunk size of 50).

🎯 Why:

Previously, importing participant/chip mapping data performed one stmt.execute(...) query per row in a loop. With large datasets (e.g. 10,000+ items), this loop query dispatch overhead created an N+1 query pattern.

📊 Measured Improvement:

Measured using benchmark_bulk_operations in release mode for 10,000 items each:

• replace_bib_chips: 15.59 ms → 8.77 ms (~43.7% faster)
• replace_divisions: 6.12 ms → 4.01 ms (~34.5% faster)
• replace_participants: 9.10 ms → 8.32 ms (~8.6% faster)
• replace_rd_data: 30.80 ms → 22.33 ms (~27.5% faster)

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PR created automatically by Jules for task 6983175102808330700 started by @iwismer

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