Add optional Iced backend: arbitrary text assembly and full prologue validation

Section 8 of the whitemagic-foundation change.

- 8.1: reference Iced 1.21.0 behind IcedAssembler:IAssembler. The default
  StubAssembler path never touches Iced; only constructing IcedAssembler pulls
  it into a behavioral path.
- 8.2: IcedAssembler.Assemble bridges Intel-syntax text onto Iced's fluent
  Assembler by reflection (Iced ships no text parser). Registers, immediates and
  labels are supported with origin-relative encoding; memory operands throw
  NotSupportedException.
- 8.3: IcedAssembler.GetPrologueLength decodes arbitrary instructions via Iced's
  Decoder. DetourManager.PrologueLengthResolver (new delegate) defaults to the
  built-in PrologueDecoder and is swappable to the Iced resolver, threaded into
  each Detour. This lifts the "partial boundary safety" caveat on the hooking
  slice when Iced is opted in.

Also gitignore test-run TestResults artifacts.

Tests: 221 passing, 4 skipped.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

openspec/changes/whitemagic-foundation/tasks.md

@@ -38,7 +38,7 @@
 - [x] 4.3 Add tests for `DetourManager`/`Detour` in-process: apply redirects, `CallOriginal`, remove restores, named lookup
 - [x] 4.4 Implement `WhiteMagic/Hooking/DetourManager.cs` + `Detour.cs` (inline jmp, x86/x64 form) to pass 4.3
 - [x] 4.5 Add tests for instruction-boundary validation (aligned splice permitted, misaligned rejected when boundary info available)
-- [x] 4.6 Implement minimal prologue length-decoder in `Detour.Apply` to pass 4.5. Default `StubAssembler` covers ONLY the common x86/x64 prologue shapes — enumerate the covered opcodes in code + XML doc (e.g. `push reg` 0x50-0x57, `mov edi,edi` 8B FF, `push ebp`/`mov ebp,esp` 55 8B EC, `sub esp,imm` 83 EC / 81 EC, REX-prefixed forms). On any opcode outside the set, refuse the splice (do not guess). Full arbitrary-prologue validation is gated on the optional Iced backend (task 8.3) — document that slices 2-5 ship partial boundary safety.
+- [x] 4.6 Implement minimal prologue length-decoder in `Detour.Apply` to pass 4.5. Default `StubAssembler` covers ONLY the common x86/x64 prologue shapes — enumerate the covered opcodes in code + XML doc (e.g. `push reg` 0x50-0x57, `mov edi,edi` 8B FF, `push ebp`/`mov ebp,esp` 55 8B EC, `sub esp,imm` 83 EC / 81 EC, REX-prefixed forms). On any opcode outside the set, refuse the splice (do not guess). Full arbitrary-prologue validation is gated on the optional Iced backend (task 8.3) — document that slices 2-5 ship partial boundary safety. **Resolved (8.3):** `DetourManager.PrologueLengthResolver` now accepts `IcedAssembler.GetPrologueLength` for full instruction-boundary validation of arbitrary prologues; the built-in decoder remains the zero-dependency default.
 - [x] 4.7 Add tests for auto-restore: disposing a `MemoryBase` reverts all active patches and detours
 - [x] 4.8 Wire manager registration + `MemoryBase.Dispose` restore to pass 4.7
 - [x] 4.9 Add tests for `MainThreadPump` queue semantics: item runs on hooked thread, result returned, throwing item surfaces exception and pump survives, dispose uninstalls hook (use a self-hosted frame-loop harness in-process)
@@ -75,9 +75,9 @@
 
 ## 8. Optional Iced Backend (spec: managed-assembler)
 
-- [ ] 8.1 Add `Iced` package reference behind an `IcedAssembler : IAssembler` in a way that keeps the default `StubAssembler` dependency-free
-- [ ] 8.2 Add tests + implement `IcedAssembler.Assemble(text, origin)` for arbitrary mnemonics and origin-relative encoding
-- [ ] 8.3 Add tests + wire full prologue instruction-boundary validation (D5) using the Iced disassembler when present
+- [x] 8.1 Add `Iced` package reference behind an `IcedAssembler : IAssembler` in a way that keeps the default `StubAssembler` dependency-free. Iced 1.21.0 added to `WhiteMagic.csproj`; only constructing `IcedAssembler` pulls it into a behavioral path. `StubAssembler` never references it.
+- [x] 8.2 Add tests + implement `IcedAssembler.Assemble(text, origin)` for arbitrary mnemonics and origin-relative encoding. **Deviation:** Iced ships a *fluent* code assembler and a decoder but **no text parser**, so `Assemble` bridges Intel-syntax text onto Iced's `Assembler` by reflection — the mnemonic selects the matching fluent method and operands bind to registers (reflected from `AssemblerRegisters`), immediates, or labels; origin-relative encoding via `Assembler.Assemble(writer, origin)`. Register/immediate/label operands and label-relative branches are supported; **memory operands (`[reg+disp]`) throw `NotSupportedException`** (a caller needing those emits bytes directly). Tests round-trip via Iced's decoder and assert origin-relative branch targets.
+- [x] 8.3 Add tests + wire full prologue instruction-boundary validation (D5) using the Iced disassembler when present. `IcedAssembler.GetPrologueLength` decodes arbitrary instructions via Iced's `Decoder`; `DetourManager.PrologueLengthResolver` (a `PrologueLengthResolver` delegate) defaults to the built-in `PrologueDecoder` and is swappable to the Iced resolver, threaded into each `Detour`. Tests prove Iced resolves a prologue (`mov rax,rcx` = `48 8B C1`) the built-in decoder rejects.
 
 ## 9. Verification