[ryanbr]

Rebase of #2654 by @kavemang onto current main. The original description there remains the authoritative account.

Rebase-merge rather than squash, so @kavemang stays the author.

What the rebase changed

Two things, both mechanical.

The docs commit 13cdde663 is dropped, because it is already on main as f8594b894 from #2653. #2654 was stacked on that same commit, so only its own change replays here: 12 files, +31/-3, where the original listed 15 files including the three guidance files.

Strand/Resources/Localizable.xcstrings conflicted. Both sides PREPEND one new key to "strings": {: main carries "Skips sessions that overlap a saved or imported workout..." from #2658, and this change adds "Requires Live Sessions to be enabled in Settings.". The catalogue is not alphabetically ordered, so the correct resolution is to keep both, which is what I did. Verified on the result rather than on the method: the file parses, holds 4171 keys (4170 + 1), carries BOTH keys, and has no duplicate key under an object_pairs_hook check, which a plain parse would hide by keeping only the last of a duplicated pair.

Verified before merge

• today_customize_live_session_availability is present in the default locale and in all eight translations, and no locale carries a key the default lacks. That last one is the ExtraTranslation class that passes compile and the i18n gate and only fails release lint.
• Tools/i18n_audit.py --ci: no new English-only translations, no new non-focus-locale gaps.
• Tools/doc_comment_lint.py: OK, no new detached doc comments.
• Tools unittest suite: OK.
• ./gradlew compileFullDebugKotlin --no-build-cache: clean. Worth running because TodayScreen.kt takes +22/-3 here, more than the one-line string additions elsewhere.
• Not run locally: the Apple half. TodayCustomizationSheet.swift takes +2, and app-target Swift needs Xcode on macOS, so the build (Strand, macOS) and build (NOOPiOS) legs on this PR are the first execution of it.

Refs #2654, #2653, #2658