feat(blur): a booth can be fogged as a whole, composing with per-item blur

The operator ruled booth-level blur in and chose reading A for the reveal
("A is fine"). design-dev specced the semantics and owns the controls; this is
the storage half.

COMPOSES, NEVER OVERRIDES. An item is blurred iff the booth is blurred OR it is
in .blurred, so turning booth blur off leaves an agent's per-item choice exactly
as the poster left it. An override would need a per-item "unblurred" exception
list, which is state nobody can see.

Resolved in booth_items, so every surface inherits it for free — Desk strip,
tiles, flag tray, filmstrip, stage all already read Item.blurred and none of
them learns the booth flag exists (INV-1). Images and video only; audio has
nothing to hide from a glance.

A MARKER, deliberately not JSON. `.seen` is JSON because it holds rels that must
round-trip exactly; a boolean has nothing to round-trip, and matching `.forever`
means the two whole-booth flags read the same way. We told design-dev it would
be JSON and it should not be — said so rather than quietly shipping the other
thing.

is_booth_blurred mirrors is_kept's lstat shape WITH THE SAFETY INVERTED, and the
inversion is the point: is_kept fails toward keeping because a failed read must
not authorise a delete; this fails toward HIDING, because a failed read must not
reveal something a poster asked to fog. Both are "the failure does not cause the
loss".

Also records the operator's 2026-09-23 ruling that there is NO 1.0 yet, and adds
.blurbooth to CLAUDE.md's dotfile list. 766 green.

ROADMAP.md

@@ -13,8 +13,11 @@ claim about now — and no further pre-release is cut until the arc lands.
 Dropping back to an alpha is not available: `1.0.0a2` sorts BELOW `1.0.0b1`, and
 versions do not go backwards.
 
-**Whether `1.0.0` waits for the redesign is the operator's call** and is not
-yet made. See the design-arc section.
+🛑 **RULED 2026-09-23: NO `1.0.0` YET.** Verbatim: *"no v1.0 yet."* The tag
+stays at `1.0.0b1`, no further pre-release is cut until the arc lands, and the
+arc now includes the flow redesign, compare mode and the Desk revisions still in
+flight. Do not cut a release because the suite is green and the roadmap looks
+complete — it has looked complete twice already.
 
 ## v1 target