refactor(agglayer): simplify stack operations and clarify FPI comments

[Copilot]

Address code review feedback to reduce cycle count and improve readability in agglayer faucet operations.

Changes

• Simplified get_origin_token_address: Replace 5-operation sequence with movdn.7 drop drop drop (fewer cycles, clearer intent)
• Improved formatting: Add blank line before repeat loop in asset_to_origin_asset
• Clarified FPI stack comments: Update bridge_out.masm to show complete stack state after execute_foreign_procedure, making it explicit that destination data remains below the 16 returned elements

-    movup.3 drop movup.2 drop swap drop
-    # => [addr4, addr0, addr1, addr2, addr3]
-
-    # Reorder to [addr0, addr1, addr2, addr3, addr4]
-    movdn.4
+    movdn.7 drop drop drop
     # => [addr0, addr1, addr2, addr3, addr4]

Note: Did not adopt sys::truncate_stack suggestions as this utility does not exist in the codebase.

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