T7.2 - F6/D3: the form gets structure - a section rail, one section open

F6 as amended by D3 (Aug 18): one page, persistent side navigation, sections
collapsible, only the current one open by default, plus Expand all. Tabs were
rejected in D3 because they hide sections a first-time author does not know
exist.

What changed:
- The jump-chip strip (#section-nav, span onclick) is gone. In its place a
  <nav> section rail of real <button> entries, aria-current on the current
  section, 44px tap targets, above the form at 390px and beside it at 1440px.
- Every section heading is now a disclosure <button> with aria-expanded and
  aria-controls. One section open at rest; Expand all (aria-pressed) opens
  everything and is remembered per browser.
- Sections are URL-addressable (?section=, T4.2 machinery) and a deep link to
  a collapsed section expands it. Positional-id fallback removed: a card
  without an id gets a console.error and no rail entry, never an invented
  sec-N id that would ride into shareable URLs and move between visits.
- General Information (1,288px on its own) split into #general-card and
  #assign-card (Assignment & Schedule). The split is presentational: both
  cards are the ONE CR-006 section `general` (WP_SECTION_NODES lists both),
  so wp-sections.js and the SOP wizard are untouched. CR-001's adjacency
  (P6 activity beside due date) is preserved and asserted.
- gotoSection() flushes autosave, which the deleted chips used to do.
- secMakeToggle() preserves every element child of a heading - help tips go
  outside the button, everything else inside the label. The first version
  cleared textContent and destroyed #saved-count, which killed boot one line
  short of wpCreatorReady with the page still visibly rendered.
- BL-013 folded in per the task: the T3.4 focus ring on the rebuilt form.
  frame_check reports outline solid 2px on creator inputs.

Height, measured not asserted: 5,399px before; 1,995px at rest at 1440x900.

DONE-WHEN NOT FULLY MET - stated per CLAUDE.md rather than marked complete:
"no single view exceeds roughly two screen heights at rest" reads 2.22
screens (1995/900). The remaining gap is page chrome this wave reworks:
.ctx-bar (67px, T7.4) and .release-banner (45px, T7.5). The criterion was
already amended once (D3, "at rest") and is not being moved again to fit;
tests/form_structure_check.py keeps the check red and it is re-measured at
the end of wave 7. Every other done-when entry passes.

Backlog: BL-001's cause corrected a third time - at rest the overflow is
help.js's .help-tip::after tooltip (481 vs 390), the S8 component T9.5
rebuilds; the tables still overflow only when expanded. Deliberately not
fixed here - a fix would be thrown away with the component at T9.5.

Verification (each probe run alone): form_structure_check 50/51 (the height
check above), sections_check 95/95, generalinfo_check 49/49, frame_check
39/39 regression pass.

Items: F6, D3, BL-013, BL-001 (re-measured)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/reference/file-map.md

@@ -260,7 +260,7 @@ python tests/stepper_check.py       # A4/S9 — ten real buttons, keyboard opera
 python tests/launcher_check.py      # B3  — can a brand-new account get started?   58 checks
 python tests/pipeline_check.py      # B4 surface — server counts, shareable links  43 checks
 python tests/locations_check.py     # CR-005 — codes not labels, nothing deleted   58 checks
-python tests/sections_check.py      # CR-006/CR-002/CR-016 — hidden, not deleted  88 checks
+python tests/sections_check.py      # CR-006/CR-002/CR-016 — hidden, not deleted  95 checks
 python tests/validation_check.py    # S1 wizard — errors at the field, no dialogs 81 checks
 ```
 
@@ -272,10 +272,11 @@ python tests/rollup_check.py        # CR-004/CR-018 — codes, and totals that a
 python tests/cards_check.py         # A7 — card status, footer, localization    44 checks
 ```
 
-Wave 7 adds one:
+Wave 7 adds these:
 
 ```bash
-python tests/frame_check.py         # B7/T7.1/D1 - is the iframe actually gone?  39 checks
+python tests/frame_check.py          # B7/T7.1/D1 - is the iframe actually gone?  39 checks
+python tests/form_structure_check.py # F6/D3 - rail, disclosure, one open section 51 checks
 ```
 
 **Three probes were re-pointed at `T7.1`.** `sections_check.py` 5b drove the live
@@ -287,6 +288,15 @@ standalone and `?embedded=1`; there is one mode now. `validation_check.py` lost
 "loading the sample on the wrong tab" case for the same reason - there is no wrong tab
 on the wizard any more - and gained one for the SOP gate instead.
 
+**Two probes were re-pointed at `T7.2`, both for the General Information split.**
+`sections_check.py`'s section table carried one selector per section; the `general` row
+now carries two (`#general-card, #assign-card`) and every hidden/shown reading walks ALL
+of a row's cards, because the failure mode the split could have had is exactly "half the
+section hidden and half still rendering". Its chip-strip reading moved to the rail
+(`#section-nav` no longer exists). `generalinfo_check.py` asserted DOM containment in
+`#general-card`; it now asserts what that containment was FOR - the CR-006 `general`
+toggle governs the P6 fields - against whichever of the two cards holds them.
+
 **Two probes were re-pointed at `T6.5`, and the reason is worth carrying forward.**
 `aggregates_check.py` matched the launcher card's exact wording (`"SOP complete"`), and it
 also waited for the status line to be non-empty — which stopped meaning "the answer has