feat(runtime): Phase 103 CoreServices Optional化 - Memory Constraints対応

- Add CoreServicesConfig struct (from_env, minimal, all_enabled)
- Implement with_core_from_registry_optional() for selective initialization
- Update CoreBoxesImpl fields to Option<Arc<dyn XyzService>>
- Maintain backward compatibility (with_core_from_registry calls all_enabled)
- Add NYASH_CORE_DISABLE_* environment variable support
- ConsoleBox remains mandatory (Graceful Degradation principle)
- Add unit tests for optional initialization
- Update console_println! macro to handle Option type
- Fix direct console.println() calls in vm.rs and selfhost.rs
- Create core_optional_design.md documentation

Note: Phase 104 will extend ConsoleService to be optional as well with
graceful fallback in console_println! macro.

Files modified:
- src/runtime/plugin_host.rs (CoreServicesConfig, with_core_from_registry_optional, tests)
- src/runtime/core_services.rs (CoreBoxesImpl fields → Option type)
- src/runtime/mod.rs (console_println! macro updated)
- src/runner/modes/vm.rs (handle Option console)
- src/runner/selfhost.rs (handle Option console)
- docs/development/current/main/core_optional_design.md (new)
- docs/development/current/main/ring0-inventory.md (Phase 103 entry)

Test results:
- Build: ✅ Success (0 errors, 7 warnings)
- Unit tests: ✅ 3/3 passed (optional_core_tests)
- Runtime tests: ✅ 63/63 passed
- Smoke tests: ✅ 30/31 passed (1 pre-existing timeout)

src/mir/basic_block.rs

@@ -6,6 +6,7 @@
 
 use super::{EffectMask, MirInstruction, SpannedInstRef, SpannedInstruction, ValueId};
 use crate::ast::Span;
+use crate::runtime::get_global_ring0;
 use std::collections::BTreeSet; // Phase 69-3: HashSet → BTreeSet for determinism
 use std::fmt;
 
@@ -294,8 +295,14 @@ impl BasicBlock {
         let phi_count = self.phi_instructions().count();
         if std::env::var("NYASH_SCHEDULE_TRACE").ok().as_deref() == Some("1") {
             if let MirInstruction::Copy { dst, src } = &instruction {
-                eprintln!("[insert-after-phis] bb={:?} phi_count={} inserting Copy dst=%{} src=%{} total_inst={}",
-                    self.id, phi_count, dst.0, src.0, self.instructions.len());
+                get_global_ring0().log.debug(&format!(
+                    "[insert-after-phis] bb={:?} phi_count={} inserting Copy dst=%{} src=%{} total_inst={}",
+                    self.id,
+                    phi_count,
+                    dst.0,
+                    src.0,
+                    self.instructions.len()
+                ));
             }
         }
         self.effects = self.effects | instruction.effects();
@@ -308,9 +315,9 @@ impl BasicBlock {
         let phi_count = self.phi_instructions().count();
         if std::env::var("NYASH_SCHEDULE_TRACE").ok().as_deref() == Some("1") {
             if let MirInstruction::Copy { dst, src } = &sp.inst {
-                eprintln!(
+                get_global_ring0().log.debug(&format!(
                     "[insert-after-phis] bb={:?} phi_count={} inserting Copy dst=%{} src=%{} total_inst={}",
-                    self.id, phi_count, dst.0, src.0, self.instructions.len());
+                    self.id, phi_count, dst.0, src.0, self.instructions.len()));
             }
         }
         self.effects = self.effects | sp.inst.effects();