Request validation and resilience improvements (#864)

### Security: Input validation & path safety
- **Reject local file references by default** in package parsing — only allow when explicitly opted in by the service (`ParseFlags::kAllowLocalReferences`) and validated by an `ILocalRefPolicy` (fail-closed: no policy = rejected)
- **`DataRootLocalRefPolicy`** restricts local ref paths to the server's data root via canonical path prefix matching
- **Validate attachment hashes** in compute HTTP handlers — decompresses and re-hashes each attachment at ingestion time to reject tampered payloads
- **Path traversal validation** for worker descriptions (`pathvalidation.h`) — rejects absolute paths, `..` components, Windows reserved device names, and invalid filename characters
- **Harden CbPackage parsing** against corrupt inputs — overflow-safe attachment count, bounds checks on local ref offset/size, graceful failure instead of `ZEN_ASSERT` for untrusted data
- **Harden legacy package parser** — reject zero-size binary fields, missing mappers, and optionally validate resolved attachment hashes
- **Bounds check in `CbPackageReader::MarshalLocalChunkReference`** — detect when `MakeFromFile` silently clamps offset+size to file size

### Reliability: Lock consolidation & bug fixes
- **Consolidate three action map locks into one** (`m_ActionMapLock`) — eliminates deadlock risk from multi-lock ordering, simplifies state transitions, and fixes a race where newly enqueued actions were briefly invisible to `GetActionResult`/`FindActionResult`
- **Fix infinite loop in `BaseRunnerGroup::SubmitActions`** when actions exceed total runner capacity — cap round-robin at `TotalCapacity` and default unassigned results to "No capacity"
- **Fix `MakeSafeAbsolutePathInPlace` for UNC paths** — `\server\share` now correctly becomes `\?\UNC\server\share` instead of `\?\server\share`
- **Fix `max_retries=0`** — previously fell through to the default of 3; now correctly means "no retries"

### New: ManagedProcessRunner
- Cross-platform process runner backed by `SubprocessManager` — uses async exit callbacks instead of polling, delegates CPU/memory metrics to the manager's built-in sampler
- `ProcessGroup` (JobObject on Windows, process group on POSIX) for bulk cancellation on shutdown
- `--managed` flag on `zen exec inproc` to select this runner
- Refactored monitor thread lifecycle — `StartMonitorThread()` now called from derived constructors to avoid calling virtual functions from base constructor

### Process management
- **Suppress crash dialogs** via `JOB_OBJECT_UILIMIT_ERRORMODE` + `SEM_NOGPFAULTERRORBOX` in both `WindowsProcessRunner` and `JobObject::Initialize` — prevents WER/Dr. Watson modal dialogs from blocking the monitor thread
- **CREATE_SUSPENDED → AssignProcessToJobObject → ResumeThread** pattern in `WindowsProcessRunner` — ensures job object assignment before process execution
- **Move stdout/stderr callbacks to `Spawn()` parameters** in `SubprocessManager` — prevents race where early output could be missed before callback installation
- Consistent PID logging across all runner types

### Test infrastructure
- **`zentest-appstub`**: Added `Fail` (configurable exit code) and `Crash` (abort / nullptr deref) test functions
- **Compute integration tests**: exit code handling, auto-retry exhaustion, manual reschedule after failure, mixed success/failure queues, crash handling (abort + nullptr), crash auto-retry, immediate query visibility after enqueue
- **Package format tests**: truncated header, bad magic, attachment count overflow, truncated data, local ref rejection/acceptance, policy enforcement (inside/outside root, traversal, no-policy fail-closed)
- **Legacy package parser tests**: empty input, zero-size binary, hash resolution with/without mapper, hash mismatch detection
- **UNC path tests** for `MakeSafeAbsolutePath`

### Misc
- ANSI color helper macros (`ZEN_RED`, `ZEN_BRIGHT_WHITE`, etc.) and `ZEN_BOLD`/`ZEN_DIM`/etc.
- Generic `fmt::formatter` for types with free `ToString` functions
- Compute dashboard: truncated hash display with monospace font and hover for full value
- Renamed `usonpackage_forcelink` → `cbpackage_forcelink`
- Compute enabled by default in xmake config (releases still explicitly disable)

1 files changed, 22 insertions, 2 deletions

diff --git a/src/zenhttp/httpserver.cpp b/src/zenhttp/httpserver.cpp
index e05c9815f..38021be16 100644
--- a/src/zenhttp/httpserver.cpp
+++ b/src/zenhttp/httpserver.cpp
@@ -479,6 +479,18 @@ HttpService::HandlePackageRequest(HttpServerRequest& HttpServiceRequest)
 	return Ref<IHttpPackageHandler>();
 }
 
+bool
+HttpService::AcceptsLocalFileReferences() const
+{
+	return false;
+}
+
+const ILocalRefPolicy*
+HttpService::GetLocalRefPolicy() const
+{
+	return nullptr;
+}
+
 //////////////////////////////////////////////////////////////////////////
 
 HttpServerRequest::HttpServerRequest(HttpService& Service) : m_Service(Service)
@@ -705,7 +717,10 @@ HttpServerRequest::ReadPayloadPackage()
 {
 	if (IoBuffer Payload = ReadPayload())
 	{
-		return ParsePackageMessage(std::move(Payload));
+		ParseFlags Flags =
+			(IsLocalMachineRequest() && m_Service.AcceptsLocalFileReferences()) ? ParseFlags::kAllowLocalReferences : ParseFlags::kDefault;
+		const ILocalRefPolicy* Policy = EnumHasAllFlags(Flags, ParseFlags::kAllowLocalReferences) ? m_Service.GetLocalRefPolicy() : nullptr;
+		return ParsePackageMessage(std::move(Payload), {}, Flags, Policy);
 	}
 
 	return {};
@@ -1273,7 +1288,12 @@ HandlePackageOffers(HttpService& Service, HttpServerRequest& Request, Ref<IHttpP
 					return PackageHandlerRef->CreateTarget(Cid, Size);
 				};
 
-				CbPackage Package = ParsePackageMessage(Request.ReadPayload(), CreateBuffer);
+				ParseFlags			   PkgFlags = (Request.IsLocalMachineRequest() && Service.AcceptsLocalFileReferences())
+													  ? ParseFlags::kAllowLocalReferences
+													  : ParseFlags::kDefault;
+				const ILocalRefPolicy* PkgPolicy =
+					EnumHasAllFlags(PkgFlags, ParseFlags::kAllowLocalReferences) ? Service.GetLocalRefPolicy() : nullptr;
+				CbPackage Package = ParsePackageMessage(Request.ReadPayload(), CreateBuffer, PkgFlags, PkgPolicy);
 
 				PackageHandlerRef->OnRequestComplete();
 			}