fix(post-sync): restore wiped public-only docs, un-flatten screenshots, restore hero swap

The first auto-sync of rx-v2.8.5 had 3 bugs that this commit hand-corrects.
The sync workflow has been patched too (see private repo) so the next
sync doesn't reintroduce these.

1. docs/ was wiped wholesale — restored:
   - docs/troubleshooting.md (the comprehensive symptom→fix reference)
   - docs/self-hosting.md (DIY broker walkthrough)
   - docs/images/legacy/ (v1.0-era pictures kept for posterity)

2. docs/firmware/screenshots/ got flattened to docs/screenshots/ —
   moved back to the full path so all wiki + README image references
   resolve again.

3. Hero right image in README was reverted by the sync to
   case-side-profile.jpg — swapped back to case-sensor-mount.jpg
   per Ravi's preference (the BSP-threaded sensor screw is more
   distinctive than the closed-case profile).

The sync workflow has been patched in private to:
- Wipe only public/docs/firmware (not all of public/docs)
- rsync docs/firmware/ → $STAGE/docs/firmware/ (preserve prefix)
- Propagate the full annotated tag body to public (not a short message)

Author: Ravi Singh

README.md

@@ -9,7 +9,7 @@ Long-range wireless water tank level monitoring using LoRa (RYLR998), ESP32, and
 
 <p align="center">
   <img src="hardware/photos/pcb-populated-top.jpg" width="45%" alt="Populated TX PCB (open hardware)" />
-  <img src="hardware/photos/case-side-profile.jpg" width="45%" alt="Assembled TX in its PETG case (current production)" />
+  <img src="hardware/photos/case-sensor-mount.jpg" width="45%" alt="BSP-threaded sensor mount installed on a tank lid (current production)" />
 </p>
 <p align="center">
   <sub><em>Custom circular TX PCB and current-production PETG enclosure (REV 2.2, May 2026) — tested through Delhi summer at 45°C ambient.</em></sub>