apollo_batcher_config: reduce proposer_idle_detection_delay 2000 -> 1500ms (SNIP-40)

[matanl-starkware]

Per SNIP-40 "More Frequent Blocks", reduce the batcher's mempool idle-detection
delay from 2.0s to 1.5s. Block cadence is driven by this delay, so this changes
the typical block execution slot from ~2s to ~1.5s.

Spec: https://community.starknet.io/t/snip-40-more-frequent-blocks/116203

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

[reviewable-StarkWare]

This change is 

[matanl-starkware]

• blockifier: increase StorageRead/Write gas costs +33% (SNIP-40) #14177
• blockifier: bump execute_max_sierra_gas 1.1B -> 1.11B (SNIP-40) #14176
• apollo_versioned_constants: reduce block gas_target 1.5B -> 1.04B (SNIP-40) #14175
• apollo_batcher_config: reduce proposer_idle_detection_delay 2000 -> 1500ms (SNIP-40) #14174 👈 (View in Graphite)
• main

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[cursor]

PR Summary

Medium Risk
Changes live block-proposal timing and network block cadence; low code complexity but operational impact on consensus and batcher behavior.

Overview
Implements SNIP-40 by lowering the batcher proposer_idle_detection_delay_millis from 2000 to 1500 everywhere it is defined.

The default in BatcherDynamicConfig, the deployment batcher_config.json, and config_schema.json are updated so that, during block proposal, the proposer can treat the mempool as idle and close the block sooner when no transactions are executing—shortening the typical block slot from ~2s toward ~1.5s.

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[dorimedini-starkware]

@dorimedini-starkware reviewed 3 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on matanl-starkware).