T9.4 - S7: one sample-data affordance, confirmed, and fenced off the project

Four affordances under three names became ONE: "Load sample data", on the
creator's toolbar, at the far end of two separators from the live actions
(New / Duplicate), pushed right with its own gap. It confirms through the
T7.9 dialog, naming exactly what it does - and what it does not: "This page
only: nothing is written to the project unless you then save." The probe
verifies the fence the way the done-when demands - against a REAL project,
reading the server's SOP and work-package list before and after and asserting
byte-identical.

Gone: the wizard's header "Load sample" (the dangerous one: it filled the
state completeSOP() pushes to the LIVE project, one click, no confirm, no
undo - reconciled with D1 exactly as the task records: the creator's control
is the survivor, the wizard copy goes), the creator's split Sample SOP /
Load example pair (now internals behind the one entry point), and the
empty-state context bar's third button (its text now points at the toolbar
control). The location/material "Load sample values" buttons stay: they fill
a PASTE BOX that acts only through an explicit, dry-runnable import - a
different thing, stated in the code.

Probes re-pointed with reasons in place: frame_check's D1 toolbar list names
the consolidated control; validation_check's sample-driven toast checks
became the-affordance-is-gone checks (and its stale showAnalytics drive,
orphaned by T7.10, became a the-duplicate-stays-gone check).

Verification (each probe run alone): NEW tests/sample_check.py 10/10.
Regressions: validation_check 77/77, frame_check 38/38, kitting_check 26/26,
export_check 20/20, sections_check 95/95.

Items: S7 (D1 reconciliation honored)

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

docs/reference/file-map.md

@@ -300,6 +300,7 @@ Wave 9 adds these:
 
 ```bash
 python tests/export_check.py         # CR-008/CR-017 - export walk + hours guard   20 checks
+python tests/sample_check.py         # S7 - one sample affordance, confirmed+fenced 10 checks
 ```
 
 **Three probes were re-pointed at `T7.1`.** `sections_check.py` 5b drove the live