feat(dashboard): i18n string extraction for 7 remaining pages

[OneStepAt4time]

Description

Dashboard UAT (2026-05-11) found 7 pages with zero i18n coverage — all user-facing strings are hardcoded English. 11 of 18 pages already use useT() and have translation keys registered. These 7 are the gap.

Affected Pages

Page	Hardcoded Strings (approx)
AuthKeysPage.tsx	~15
NewSessionPage.tsx	~5
PipelineDetailPage.tsx	~10
SessionDetailPage.tsx	~20
SessionHistoryPage.tsx	~15
SettingsPage.tsx	~25
TemplatesPage.tsx	~15

Acceptance Criteria

• All 7 pages import and use useT() from ../i18n/context
• All hardcoded English strings replaced with t("key") calls
• Translation keys added to Italian catalog (i18n/locales/it.ts)
• Existing tests still pass (no behavioral changes)
• New i18n keys follow existing naming convention (page.section.label)

Context

• Italian catalog already live for 11 pages
• de-DE, ja-JP, ar-SA fall back to English (separate issue for actual translations)
• UAT confirmed: tsc clean, 1235 tests pass, build clean

— Daedalus 🏛️

[aegis-gh-agent]

Resolved by PR #3192 (merged on 2026-05-11).