fix: the recovery page's globe must write the HOUSEHOLD's setting, not a cookie nothing reads

/recovery is in the AUTHENTICATED route table — its reader is the household, not a visitor. The
first draft of v0.254.0 gave it the anonymous form, which sets the felhom_lang cookie that
langFor deliberately ignores once there is a session: the button would have appeared to work
and done nothing. Found by the live probe on demo-hp reporting no globe on /recovery (it 302s
to /login without a session) and then reading the route table.

executeTemplateLang now branches on hasSession: household form with its session CSRF, or the
visitor form without. The parity harness and TestI18nDirectRenderPagesFollowLanguage carry the
same branch, so the fixture is the form the real page serves — the trap this release already
walked into once with the shells.

A per-session CSRF token cannot be a fixture value, so it is blanked on both sides of every
parity comparison, exactly as relative ages already were. What stays pinned is that the field is
THERE and WHICH form it sits in — the half that says whether the globe writes the household's
setting or the visitor's cookie.

Evidence regenerated: 3 change shapes across 106 fixtures, 5 byte-identical (both guest share
pages and the catch-all — the three that must not change).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/testdata/i18n_parity/stacks_full.html

@@ -150,8 +150,8 @@
                 <span class="version">0.247.0</span><details class="lang-globe">
     <summary class="lang-globe-btn" aria-label="Nyelv" title="Nyelv"><svg class="ico" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><circle cx="12" cy="12" r="10" /><path d="M2 12h20" /><path d="M12 2a15.3 15.3 0 0 1 4 10 15.3 15.3 0 0 1-4 10 15.3 15.3 0 0 1-4-10 15.3 15.3 0 0 1 4-10z" /></svg></summary>
     <ul class="lang-globe-menu">
-        <li><form method="POST" action="/settings/language"><input type="hidden" name="_csrf" value=""><input type="hidden" name="back" value="/i18n-fixture"><button type="submit" name="lang" value="hu" lang="hu" class="lang-globe-item current" aria-current="true">Magyar</button></form></li>
-        <li><form method="POST" action="/settings/language"><input type="hidden" name="_csrf" value=""><input type="hidden" name="back" value="/i18n-fixture"><button type="submit" name="lang" value="en" lang="en" class="lang-globe-item">English</button></form></li>
+        <li><form method="POST" action="/settings/language"><input type="hidden" name="_csrf" value="CSRF"><input type="hidden" name="back" value="/i18n-fixture"><button type="submit" name="lang" value="hu" lang="hu" class="lang-globe-item current" aria-current="true">Magyar</button></form></li>
+        <li><form method="POST" action="/settings/language"><input type="hidden" name="_csrf" value="CSRF"><input type="hidden" name="back" value="/i18n-fixture"><button type="submit" name="lang" value="en" lang="en" class="lang-globe-item">English</button></form></li>
     </ul>
 </details>
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