feat: Add Smart Escrow fee voting

Add `GasLimit`, `BytecodeSizeLimit`, and `GasPrice` to the network's votable
fee settings, gated on `featureSmartEscrow`.

The `.macro` and autogen plumbing for these fields landed in #8157; this adds
the behavior behind them: config parsing, fee voting, the `SetFee` pseudo-
transaction, `FeeSettings` genesis and load, and the RPC surfaces that report
fee settings.

`detail::VotableValue` in FeeVoteImpl.cpp becomes a template, since the three
new settings are `std::uint32_t` rather than `XRPAmount`.

`ServiceRegistry::getFees()` exposes the configured settings to code that has
no `ReadView`. It has no production caller yet; the Smart Escrow transactors
call it from `preflight`.

include/xrpl/config/Constants.h

@@ -94,6 +94,7 @@ struct Keys
     static constexpr auto kBbtOptions = "bbt_options";
     static constexpr auto kBgThreads = "bg_threads";
     static constexpr auto kBlockSize = "block_size";
+    static constexpr auto kBytecodeSizeLimit = "bytecode_size_limit";
     static constexpr auto kCacheAge = "cache_age";
     static constexpr auto kCacheMb = "cache_mb";
     static constexpr auto kCacheSize = "cache_size";
@@ -108,6 +109,8 @@ struct Keys
     static constexpr auto kFileSizeMult = "file_size_mult";
     static constexpr auto kFilterBits = "filter_bits";
     static constexpr auto kFilterFull = "filter_full";
+    static constexpr auto kGasLimit = "gas_limit";
+    static constexpr auto kGasPrice = "gas_price";
     static constexpr auto kHardSet = "hard_set";
     static constexpr auto kHighThreads = "high_threads";
     static constexpr auto kHoldTime = "hold_time";

include/xrpl/core/ServiceRegistry.h

@@ -6,6 +6,7 @@
 #include <xrpl/basics/TaggedCache.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/Fees.h>
 
 #include <boost/asio.hpp>
 
@@ -246,6 +247,9 @@ public:
     virtual DatabaseCon&
     getWalletDB() = 0;
 
+    [[nodiscard]] virtual Fees
+    getFees() const = 0;
+
     // Temporary: Get the underlying Application for functions that haven't
     // been migrated yet. This should be removed once all code is migrated.
     virtual Application&

include/xrpl/protocol/Fees.h

@@ -10,6 +10,15 @@ namespace xrpl {
 // This was the reference fee units used in the old fee calculation.
 inline constexpr std::uint32_t kFeeUnitsDeprecated = 10;
 
+// Number of micro-drops in one drop.
+constexpr std::uint32_t microDropsPerDrop{1'000'000};
+
+/**
+ * Maximum Feature Extension fee settings.
+ */
+inline constexpr std::uint32_t kMaxGasLimit{2'000'000};
+inline constexpr std::uint32_t kMaxBytecodeSizeLimit{200'000};
+
 /**
  * Reflects the fee settings for a particular ledger.
  *
@@ -33,6 +42,21 @@ struct Fees
      */
     XRPAmount increment{0};
 
+    /**
+     * @brief Gas limit for Feature Extensions (instructions).
+     */
+    std::uint32_t gasLimit{0};
+
+    /**
+     * @brief Bytecode size limit for Feature Extensions (bytes).
+     */
+    std::uint32_t bytecodeSizeLimit{0};
+
+    /**
+     * @brief Price of WASM gas (micro-drops).
+     */
+    std::uint32_t gasPrice{0};
+
     explicit Fees() = default;
     Fees(Fees const&) = default;
     Fees&

include/xrpl/protocol/jss.h

@@ -252,6 +252,9 @@ JSS(expected_date);                  // out: any (warnings)
 JSS(expected_date_UTC);              // out: any (warnings)
 JSS(expected_ledger_size);           // out: TxQ
 JSS(expiration);                     // out: AccountOffers, AccountChannels, ValidatorList, amm_info
+JSS(gas_limit);                      // out: NetworkOPs
+JSS(bytecode_size_limit);            // out: NetworkOPs
+JSS(gas_price);                      // out: NetworkOPs
 JSS(fail_hard);                      // in: Sign, Submit
 JSS(failed);                         // out: InboundLedger
 JSS(feature);                        // in: Feature