DOC-1: operator docs name the real P1 entity and a roster that starts

- DOCS.md / config.yaml: the watchdog's P1 age entity is
  sensor.goodwe_p1_sample_age (device "GoodWe" + "P1 sample age", as
  app/mqtt.py announces and the live install recorded), not
  sensor.p1_sample_age_s.
- DOCS.md: the inverters: example and per-entry table carry the required
  bms_soc_floor (and capacity_kwh); config.yaml's schema comment says four
  required keys, not three.
- Field guide: marked v0.1.0/outdated; slew_w row no longer recommends the
  1000 W that SAFETY-39 now refuses. HTML regenerated; the PDF is NOT
  rebuilt (no Chrome here). README/DOCS pointers fixed.
- test_docs.py: the documented roster must pass app/validate.py and the
  schema's per-entry keys; the documented entity id must equal the id
  composed from app/mqtt.py; the wrong id may appear in no shipped doc.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwRLw7eKYj2byVdwB6kbjU

FIELD-GUIDE.md

@@ -4,6 +4,10 @@ The guide technicians carry is the PDF:
 
 **`docs/GoodWe-RS485-Field-Guide.pdf`** — 10 pages, A4, print it double-sided.
 
+⚠️ **Outdated: it is v0.1.0.** Its `slew_w` row is corrected in `build_guide.py`
+and `field-guide.html`, but the PDF has not been rebuilt (see below). Where the
+guide disagrees with `goodwe_controller/DOCS.md`, DOCS.md wins.
+
 It covers, in the order the work is done: pre-visit checks, hardware, firmware,
 add-on install and configuration, how to read the Web UI, the six commissioning
 gates, the e-stop (and the statement a site without one must sign), proving a
@@ -18,7 +22,8 @@ copy cannot drift from the PDF someone is holding in a cellar.
 python3 docs/build_guide.py     # regenerates field-guide.html and the PDF
 ```
 
-Requires Chrome or Chromium (used headless for print-to-PDF). Screenshots live
+Requires Chrome or Chromium (used headless for print-to-PDF); `CHROME` in the
+script is a Windows path, so edit it on any other machine. Screenshots live
 in `docs/img/` and are base64-embedded, so `field-guide.html` is standalone.
 
 ⚠️ **Every section must stay under the A4 printable height** (1039 px at 96 dpi