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

docs/decisions/0008-panel-devenv-positioning.md

@@ -0,0 +1,28 @@
+# ADR 0008 — Panel Development Environment
+
+**Status:** Accepted (2026-08-30).
+
+## Context
+warden-sdk was written as the SDK for WardenOS, and its documentation framed
+it that way: a support repo for one product. Since going public (ADR-0007,
+GPL-2.0-only), the actual audience is wider — anyone with a Luckfox Pico 86
+Panel gets a maintained 6.18 kernel, an off-device development loop, and a
+device simulator out of this repo, none of which exists elsewhere for this
+board. The product-first framing undersold that and confused the entry point
+for outside readers.
+
+## Decision
+Position warden-sdk as **a modern, open development environment for the
+Luckfox Pico 86 Panel (RV1106)**. WardenOS is documented as the downstream
+consumer it is, not the purpose. Documentation follows three rules: lead with
+the board, not the product; keep private-repo references clearly marked as
+context; keep titles short — a heading names a section, it does not summarize
+it.
+
+## Consequences
+- README and top-level docs lead with the hardware and the developer loop
+  (build, simulate, test), with verified quick-start commands.
+- WardenOS/flare-edge specifics stay where they are engineering truth (the
+  seam inventory, scenario payloads) but read as one consumer's usage.
+- The honesty rule is unchanged: emulation results are never on-silicon
+  claims.