feat: add MultiHookRouter for composable per-job hooks

[ariessa]

Problem

Each ERC-8183 job can only attach one hook. Jobs needing multiple concerns (escrow, privacy, reputation) must cram everything into a single monolithic contract — hard to build, hard to audit, impossible to reuse.

Additionally, BaseACPHook's setBudget selector still used the old 3-param signature setBudget(uint256,uint256,bytes) while AgenticCommerce expects setBudget(uint256,address,uint256,bytes). This meant _preSetBudget and _postSetBudget callbacks silently never fired.

Solution

• Add MultiHookRouter — implements IACPHook, fans out beforeAction/afterAction to an ordered list of sub-hooks per job. No core contract changes needed.
• Fix BaseACPHook setBudget selector, abi.decode, and virtual signatures to include the token parameter
• Update FundTransferHook and BiddingHook _preSetBudget overrides to match
• Update acp submodule to latest (evaluation grace period, expired open jobs)
• Add documentation with overview and flow diagrams