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, 12 insertions, 10 deletions

diff --git a/src/zenutil/include/zenutil/process/subprocessmanager.h b/src/zenutil/include/zenutil/process/subprocessmanager.h
index 4a25170df..e16c0c446 100644
--- a/src/zenutil/include/zenutil/process/subprocessmanager.h
+++ b/src/zenutil/include/zenutil/process/subprocessmanager.h
@@ -95,14 +95,19 @@ public:
 	/// Spawn a new child process and begin monitoring it.
 	///
 	/// If Options.StdoutPipe is set, the pipe is consumed and async reading
-	/// begins automatically. Similarly for Options.StderrPipe.
+	/// begins automatically. Similarly for Options.StderrPipe. When providing
+	/// pipes, pass the corresponding data callback here so it is installed
+	/// before the first async read completes — setting it later via
+	/// SetStdoutCallback risks losing early output.
 	///
 	/// Returns a non-owning pointer valid until Remove() or manager destruction.
 	/// The exit callback fires on an io_context thread when the process terminates.
 	ManagedProcess* Spawn(const std::filesystem::path& Executable,
 						  std::string_view			   CommandLine,
 						  CreateProcOptions&		   Options,
-						  ProcessExitCallback		   OnExit);
+						  ProcessExitCallback		   OnExit,
+						  ProcessDataCallback		   OnStdout = {},
+						  ProcessDataCallback		   OnStderr = {});
 
 	/// Adopt an already-running process by handle. Takes ownership of handle internals.
 	ManagedProcess* Adopt(ProcessHandle&& Handle, ProcessExitCallback OnExit);
@@ -182,12 +187,6 @@ public:
 	/// yet computed.
 	[[nodiscard]] float GetCpuUsagePercent() const;
 
-	/// Set per-process stdout callback (overrides manager default).
-	void SetStdoutCallback(ProcessDataCallback Callback);
-
-	/// Set per-process stderr callback (overrides manager default).
-	void SetStderrCallback(ProcessDataCallback Callback);
-
 	/// Return all stdout captured so far. When a callback is set, output is
 	/// delivered there instead of being accumulated.
 	[[nodiscard]] std::string GetCapturedStdout() const;
@@ -237,11 +236,14 @@ public:
 	/// Group name (as passed to CreateGroup).
 	[[nodiscard]] std::string_view GetName() const;
 
-	/// Spawn a process into this group.
+	/// Spawn a process into this group. See SubprocessManager::Spawn for
+	/// details on the stdout/stderr callback parameters.
 	ManagedProcess* Spawn(const std::filesystem::path& Executable,
 						  std::string_view			   CommandLine,
 						  CreateProcOptions&		   Options,
-						  ProcessExitCallback		   OnExit);
+						  ProcessExitCallback		   OnExit,
+						  ProcessDataCallback		   OnStdout = {},
+						  ProcessDataCallback		   OnStderr = {});
 
 	/// Adopt an already-running process into this group.
 	/// On Windows the process is assigned to the group's JobObject.