Reorganise into two books plus shared theory and essays

theory/                 EVIDENCE.md + THEORY.md, shared by everything
  a-days-walk/            Book One: CHAPTERS, CRAFT, FIELD_BRIEF, OUTLINE, drafts/
  seasonal-intelligence/  Book Two: OUTLINE
  essays/                 the six pieces
  archive/                superseded originals, unmaintained by design
  PORTFOLIO.md            the split and the sequence

Adds a README to each directory. Cross-references updated to the new
layout; archive/ references left broken deliberately, as those are
historical documents.

Also revises chapter 6 of Book One: the notification scene is now four
items rather than four hundred, since the narrator is a light user. The
low volume is stronger evidence than a flood would have been - it is the
case the attention-economy account cannot explain. Tracked as A26 in the
argument ledger, planted in the prologue and chapter 1.

archive/README.md

@@ -0,0 +1,10 @@
+# Archive
+
+The originals, unchanged.
+
+- **`THEORY_v1.md`** — the Cognitive Balance Theory as it stood before the July 2026 revision, reconstructed from the original 126-message ChatGPT thread (July 2025 – March 2026).
+- **`BOOK_OUTLINE_v1.md`** — the original fourteen-chapter outline, including the full Czech table of contents, all the title options, and the reading list. The Czech material and the reading list are still live and worth mining.
+
+**These files are not maintained.** Their internal cross-references point at the pre-restructure layout and no longer resolve; that's deliberate. They're historical documents, not working ones.
+
+Nothing was thrown away in the restructure. If something appears to have vanished from the current outline, it's here — check before assuming it was lost. What was *deliberately* cut, and the reasons, is recorded at the end of `../theory/THEORY.md`.