fix(as-S5a): every control named, one h1 and a skip link, rings and hit areas

The markup and CSS half of the anti-slop interaction work. The in-place
client is untouched (that is S5b).
- Glyph-only controls carry a name: the withdraw ×s, downloads, open full
  page, the viewers' ✕, the board's pin, copy and remove, the bench's
  remove, the 1:1 toggle ("1:1, natural pixels"). Film-strip and tray
  frames carry the file's name as sr-only text instead of reading "01".
  A Desk row's wipe names its booth.
- Fields are named by aria-label, not by their placeholder.
- The inline ask's options are a radiogroup labelled by the prompt; a
  single-question fieldset gets an sr-only legend; a titled ask's title
  takes bk-ask-<id>-title (it duplicated the question's id).
- One h1 per page (sr-only on the Desk, review and compare), a skip link
  to <main id="main">, theme-color for light and dark.
- The review tape is one picture (role=img); its segments leave the tab
  order (the film strip holds the same links, named).
- Wipe now uses the Desk's delegated prompt, moved to base.html: it names
  the booth and asks the kept-booth question for a kept booth.
- Embed focus rings of its own; rings drawn inside clipping containers;
  the withdraw × at least 24px, 44px under a coarse pointer;
  touch-action:manipulation; strips contain their overscroll; a long
  slug wraps on a phone.
- A truncated why carries its full text in title; a countdown of 48h or
  more reads in days.
Two r2_flow.toml rows for the confirm helper now name base.html, where
the helper moved (anchors unchanged; the gate found them drifted).

Contract: as_antislop S5a. Falsifiers: antislop.toml 86/86 proved (S1-S6, S5a);
all 12 tables 366/366 proved on this tree.

tests/mutations/r2_flow.toml

@@ -187,7 +187,7 @@ new = '''
 
 [[mutation]]
 label = "the wipe dialog shows the agent-made name raw (bidi, newline)"
-file = "booth/templates/index.html"
+file = "booth/templates/base.html"   # as S5a: the confirm helper moved here from index.html
 test = "tests/test_flow_browser.py::test_the_wipe_dialog_shows_what_is_being_wiped_and_never_fails_open"
 old = '''
       if (!confirm(word(shown(form.getAttribute('data-booth') || '')))) ev.preventDefault();'''
@@ -196,7 +196,7 @@ new = '''
 
 [[mutation]]
 label = "an unknown data-confirm word submits with no prompt (fail open)"
-file = "booth/templates/index.html"
+file = "booth/templates/base.html"   # as S5a: the confirm helper moved here from index.html
 test = "tests/test_flow_browser.py::test_the_wipe_dialog_shows_what_is_being_wiped_and_never_fails_open"
 old = '''
       var word = WORDS[form.getAttribute('data-confirm')] || ASK;