refactor(joinir): Eliminate call instruction generation duplication

Problem:
- 3 duplicate call instruction patterns
- Lines ~404-417 (handle_call non-tail)
- Lines ~506-518 (exit block tail call)
- Lines ~530-540 (unconditional jump tail call)

Solution:
- Use existing call_generator.rs helpers
- emit_call_pair() for current_instructions (no separate spans)
- emit_call_pair_with_spans() for BasicBlock with spans

Result:
- ✅ ~15 lines eliminated (3 duplicate patterns removed)
- ✅ Tests pass, no regression
- ✅ Cleaner handle_jump implementation

🤖 Generated with Claude Code

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/mir/join_ir_vm_bridge/joinir_block_converter.rs

@@ -13,6 +13,7 @@ use crate::mir::types::ConstValue;
 use std::collections::BTreeMap;
 
 use super::block_allocator::BlockAllocator; // Phase 269 P1.2+: Use BlockAllocator for deduplication
+use super::call_generator::{emit_call_pair, emit_call_pair_with_spans}; // Phase 269 P1.2+: Call instruction deduplication
 use super::merge_variable_handler::{emit_merge_copies, MergeBranch}; // Phase 269 P1.2+: Merge copy deduplication
 use super::{convert_mir_like_inst, join_func_name, JoinIrVmBridgeError};
 
@@ -400,21 +401,16 @@ impl JoinIrBlockConverter {
             ));
         }
 
-        self.current_instructions.push(MirInstruction::Const {
-            dst: func_name_id,
-            value: crate::mir::ConstValue::String(func_name),
-        });
-
         match dst {
             Some(result_dst) => {
                 // Non-tail call
-                self.current_instructions.push(MirInstruction::Call {
-                    dst: Some(*result_dst),
-                    func: func_name_id,
-                    callee: None,
-                    args: args.to_vec(),
-                    effects: EffectMask::PURE,
-                });
+                emit_call_pair(
+                    &mut self.current_instructions,
+                    func_name_id,
+                    *result_dst,
+                    &func_name,
+                    args,
+                );
             }
             None => {
                 // Tail call
@@ -507,19 +503,14 @@ impl JoinIrBlockConverter {
                 let mut exit_block = crate::mir::BasicBlock::new(exit_block_id);
 
                 // Phase 256 P1.9: Generate tail call to continuation
-                exit_block.instructions.push(MirInstruction::Const {
-                    dst: func_name_id,
-                    value: crate::mir::ConstValue::String(cont_name.clone()),
-                });
-                exit_block.instruction_spans.push(Span::unknown());
-                exit_block.instructions.push(MirInstruction::Call {
-                    dst: Some(call_result_id),
-                    func: func_name_id,
-                    callee: None,
-                    args: args.to_vec(),
-                    effects: EffectMask::PURE,
-                });
-                exit_block.instruction_spans.push(Span::unknown());
+                emit_call_pair_with_spans(
+                    &mut exit_block.instructions,
+                    &mut exit_block.instruction_spans,
+                    func_name_id,
+                    call_result_id,
+                    &cont_name,
+                    args,
+                );
                 exit_block.set_terminator(MirInstruction::Return { value: Some(call_result_id) });
                 exit_block.set_return_env(crate::mir::EdgeArgs {
                     layout: JumpArgsLayout::CarriersOnly,
@@ -536,17 +527,13 @@ impl JoinIrBlockConverter {
             None => {
                 // Unconditional jump → tail call to continuation
                 // Finalize current block with tail call
-                self.current_instructions.push(MirInstruction::Const {
-                    dst: func_name_id,
-                    value: crate::mir::ConstValue::String(cont_name),
-                });
-                self.current_instructions.push(MirInstruction::Call {
-                    dst: Some(call_result_id),
-                    func: func_name_id,
-                    callee: None,
-                    args: args.to_vec(),
-                    effects: EffectMask::PURE,
-                });
+                emit_call_pair(
+                    &mut self.current_instructions,
+                    func_name_id,
+                    call_result_id,
+                    &cont_name,
+                    args,
+                );
 
                 let return_terminator = MirInstruction::Return { value: Some(call_result_id) };