Add missing DESCRIPTION metadata across RPC methods

[Copilot]

Forest’s OpenRPC surface had many RpcMethod implementations without DESCRIPTION, which degraded generated API docs. This change fills that gap across the RPC method set, aligning with Lotus wording where possible.

• Description coverage

  • Added const DESCRIPTION: Option<&'static str> to all RpcMethod impls that were missing it in src/rpc/methods/*.
  • Includes core namespaces (chain, state, wallet, net, auth, sync, eth, msig, etc.) and Forest/F3-specific methods.

• Lotus alignment + fallback strategy

  • Reused Lotus OpenRPC summaries when available.
  • For methods without Lotus equivalents (Forest/F3/custom endpoints), added concise method-level descriptions using a consistent fallback pattern.

• OpenRPC output updates

  • Updated OpenRPC snapshots to reflect the now-populated description fields for methods in v0/v1/v2 specs.

impl RpcMethod<2> for EthTraceReplayBlockTransactions {
    const NAME: &'static str = "Filecoin.EthTraceReplayBlockTransactions";
    const NAME_ALIAS: Option<&'static str> = Some("trace_replayBlockTransactions");
    const DESCRIPTION: Option<&'static str> = Some(
        "Replays all transactions in a block returning the requested traces for each transaction.",
    );
    // ...
}

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[LesnyRumcajs]

my expectations were low, yet I was still let down