rename the crash reporter off its Chromium origins

Nothing Chromium-derived is left in either file - the stack tracer that
came from base/debug_util was the last of it - so the copyright header
credited Google for code it did not write and pointed at a LICENSE file
this repository does not have. Rename to what the files actually are.

While in there: say what the exception code's customer bit does and does
not guarantee, and note next to it how to stop a debugger breaking on
every assertion, which is what someone will be looking for when they grep
that number.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

sgp/crash_report.h

@@ -0,0 +1,52 @@
+// Crash reporting: capture a fault (or an assertion) as a report file, and hand
+// the pending reports to the telemetry uploader at startup.
+
+#ifndef SGP_CRASH_REPORT_H_
+#define SGP_CRASH_REPORT_H_
+
+struct _EXCEPTION_POINTERS;
+
+// Assertion failures raise this software exception so they get the same crash
+// report as a real fault. Bit 29 set marks it customer-defined, which keeps it out
+// of the system's own codes; the top two bits mark it an error. Other user-mode
+// producers set that bit too (MSVC's C++ exception is 0xE06D7363), so it is the
+// whole value that makes this code ours, not the bit alone.
+// A debugger sees this first-chance on every assert; `sxi e1a55e27` in WinDbg
+// (Debug > Exceptions in Visual Studio) stops it breaking.
+#define SGP_EXCEPTION_ASSERT 0xE1A55E27
+
+namespace sgp
+{
+	// Raise SGP_EXCEPTION_ASSERT and swallow it again, so the vectored crash
+	// handler writes a report for an assertion that never faults. Carries the
+	// assert's line, file and message (NULL for a plain Assert) as exception
+	// parameters.
+	void raiseAssertException(unsigned lineNum, const char* sourceFileName,
+		const char* message);
+
+	// Write a heap-free crash report (registers + a raw return-address backtrace)
+	// for the faulting context to a numbered crash_report file; symbolize it
+	// offline against the build's PDB. Call first-chance from a vectored handler.
+	void writeExceptionBacktrace(_EXCEPTION_POINTERS* ep);
+
+	// Record the build-id (game version string) to stamp into crash reports, so
+	// a report can be matched to the exact build's PDB. Call once at startup.
+	void setCrashBuildId(const char* id);
+
+	// What to tell the player: why we died and where the report landed. NULL if
+	// no crash was recorded. Built by the handler, shown from the exit path.
+	const wchar_t* crashReportMessage();
+
+	// Record the player's optional self-chosen handle (HANDLE in Ja2 Settings) to
+	// stamp into crash reports, so a report can be tied to whoever raises it with
+	// us on Discord. Empty or unset simply omits the field. Call once at startup.
+	void setCrashUserHandle(const wchar_t* handle);
+
+	// Startup crash-telemetry pass (heap is healthy here — never call from a
+	// crash handler). If url is empty the feature is off. On first run, asks the
+	// player for consent (native dialog) and remembers it; if granted, POSTs each
+	// pending crash_report_*.txt to url and deletes the ones that upload cleanly.
+	void processCrashTelemetry(const wchar_t* url);
+}
+
+#endif  // SGP_CRASH_REPORT_H_