fix(t5s3-epaper): 40MHz octal PSRAM; guard EInk init; esp32s3 sw-atomic shim (#11062)

- t5s3-epaper: the board's 3.3V octal (AP_3v3) PSRAM is unreliable at the qio_opi
  default of 80MHz (Total PSRAM reads 0, display dead / boot-loop); clock it at 40MHz.
- EInkParallelDisplay: skip EInk init and no-op display ops when the PSRAM framebuffer
  is unavailable, so the node boots headless instead of hard-faulting on a NULL buffer.
- src/platform/esp32: weak software __atomic_*_{1,2,4} so esp32s3 links on toolchains
  (e.g. macOS) that lack the sized libcalls GCC emits under -mdisable-hardware-atomics.

src/graphics/EInkParallelDisplay.h

@@ -40,6 +40,9 @@ class EInkParallelDisplay : public OLEDDisplay
     uint32_t lastDrawMsec = 0;
     FASTEPD *epaper;
 
+    // Set only when connect() fully succeeds; framebuffer-touching methods no-op while false.
+    bool displayReady = false;
+
   private:
     // Async full-refresh support
     std::atomic<bool> asyncFullRunning{false};