refactor(lee): migrate ChainedCall/Message program reference from ProgramId to AccountId

Chained-call and public-transaction dispatch now address the target
program directly by AccountId instead of routing through ProgramId and
converting internally, closing the gap that blocked PDA-addressed
program invocation. The field is named program_account_id (not
account_id) to stay unambiguous next to the account_ids list it sits
beside in the same structs.

Execution/PDA-derivation logic that fundamentally needs the RISC0 image
id (self_program_id, caller_program_id, env::verify, PDA seed
derivation) stays ProgramId-typed, recovering it from the dispatched
AccountId via the existing bijection where needed.

test_programs/guest/src/bin/chain_caller.rs

@@ -37,7 +37,7 @@ fn main() {
     let mut chained_calls = Vec::new();
     for _i in 0..num_chain_calls {
         let new_chained_call = ChainedCall {
-            program_id: auth_transfer_id,
+            program_account_id: auth_transfer_id.into(),
             instruction_data: instruction_data.clone(),
             pre_states: vec![running_sender_pre.clone(), running_recipient_pre.clone()], /* <- Account order permutation here */
             pda_seeds: pda_seed.iter().copied().collect(),

test_programs/guest/src/bin/clock_chain_caller.rs

@@ -28,7 +28,7 @@ fn main() {
         .collect();
 
     let chained_call = ChainedCall {
-        program_id: clock_program_id,
+        program_account_id: clock_program_id.into(),
         instruction_data: to_vec(&timestamp).unwrap(),
         pre_states: pre_states.clone(),
         pda_seeds: vec![],

test_programs/guest/src/bin/faucet_chain_caller.rs

@@ -29,7 +29,7 @@ fn main() {
     let [faucet_pre, vault_pda_pre] = [pre_states[0].clone(), pre_states[1].clone()];
 
     let chained_calls = vec![ChainedCall {
-        program_id: faucet_program_id,
+        program_account_id: faucet_program_id.into(),
         instruction_data: to_vec(&faucet_core::Instruction::GenesisTransferVault {
             vault_program_id,
             recipient_id,

test_programs/guest/src/bin/pda_spend_proxy.rs

@@ -31,7 +31,7 @@ fn main() {
     first_for_callee.is_authorized = true;
 
     let chained_call = ChainedCall {
-        program_id: auth_transfer_id,
+        program_account_id: auth_transfer_id.into(),
         instruction_data: to_vec(&authenticated_transfer_core::Instruction::Transfer { amount })
             .unwrap(),
         pre_states: vec![first_for_callee, second.clone()],