docs: reposition as the 86 Panel development environment

The repo's documentation framed it as a support repo for one product
(WardenOS). Since going public the real audience is anyone with a Luckfox
Pico 86 Panel: a maintained 6.18 kernel, an off-device development loop,
and a device simulator that exist nowhere else for this board. Reframe the
README and top-level docs board-first, with WardenOS documented as the
downstream consumer it is (ADR-0008).

Also an editorial pass over the whole doc set:
- every H1/H2 is now a short title, not a sentence (ADRs, qemu/, patches/,
  drivers/, architecture, NPU feasibility, config-lint, payload); workflow
  flowchart titles fixed at the source in tools/flowgen.py and regenerated
  with fresh bench numbers
- README Quick Start commands verified against the scripts; requirements
  corrected (curl, bare python, gcc >= 14) and the MC/DC gate added as a
  step (run green locally on gcc 14.2)
- dropped the 'needs python (not python3)' vendor dig: build-kernel.sh
  inherited the same requirement (filed #10 to remove it)
- glossed MC/DC and HPMCU on first use; marked the tests/uboot-ab
  reference as flare-edge; deduplicated the three-simulator list into the
  root README table

patches/README.md

@@ -1,4 +1,4 @@
-# RV1106 kernel patch series (pristine linux-6.18.46 → WardenOS)
+# The Kernel Patch Series
 
 The delta that forward-ports the vendor Rockchip 5.10.160 RV1106 support onto a
 pristine upstream **linux-6.18.46**, as a reviewable, subsystem-split series. Every
@@ -9,7 +9,7 @@ reproduces the 223-file / ~136K-line delta that boots and is hardware-verified o
 Build it with `../build/build-kernel.sh` (fetch pristine → apply these → configure
 with `../build/warden_defconfig` → `zImage` + `rv1106-warden.dtb`).
 
-## The series
+## The Series
 
 | Patch | Scope |
 |---|---|