Evaluate intentionally-left off-scale spacing values (bucket B & C)

[dprodger]

Follow-up to #199.

During the #199 spacing-token adoption, some off-scale spacing/padding values were deliberately left as literals rather than snapped to the scale. This ticket is to decide their long-term treatment: introduce extended/component tokens, or keep them as documented intentional exceptions.

Bucket B — component-internal / structural (likely keep, or add named tokens)

• Badge / pill insets: .padding(6), .padding(.vertical, 6), .padding(.vertical, 2) — e.g. RecordingRowView, AuthorityRecommendationView, RecordingDetailView, ArtistImageCarousel (PageDots), CommunityDataSection chips.
• Button / toast vertical padding: 14 — ApproachNoteButton, ToastView.
• DetailHeader title horizontal inset: 64 — clears the nav circle buttons.
• Settings sub-item leading indent: 48 — SettingsView.

Bucket C — large page-level spacing (auth / onboarding / hero / empty-state)

• 28 / 30 / 32 / 40 / 60 across the auth views, OnboardingPages / OnboardingView, AddToRepertoireSheet, AboutView, RecordingsListView, and empty-state paddings in RecordingsSection / PerformerRecordingsSection.

Decision needed

Per bucket, either:

• (a) introduce extended/component tokens — e.g. spacingXXL = 32, spacingXXXL = 40; a badge-inset token; a control vertical-padding token; or
• (b) keep as intentional literals, documented as exceptions in doc/design/layout.md.

Ref: doc/design/layout.md spacing scale; #199.

[dprodger]

Progress: Button / toast vertical padding (Bucket B) — resolved in #203

The 14pt button/toast slice is done, with a per-component decision since the two shared the value but not the intent:

• ApproachNoteButton — kept at 14pt, but introduced a named component token ApproachNoteTheme.controlVerticalPadding. It sizes the pill's tap-target height (not inter-element rhythm), so it deliberately sits outside the spacing scale, between sm(12) and md(16). This is treatment (a) — a control vertical-padding token — for the button. No visual change.
• ToastView — snapped to spacingMD (16), treatment effectively folding it back onto the scale. Its padding is card breathing room, not a tap target. Toast card is ~4pt taller as a result.

Both documented in doc/design/layout.md under a new "Component metrics (intentionally off-scale)" subsection.

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Still open

Bucket B (remaining)

• Badge / pill insets: .padding(6), .padding(.vertical, 6), .padding(.vertical, 2) — RecordingRowView, AuthorityRecommendationView, RecordingDetailView, ArtistImageCarousel (PageDots), CommunityDataSection chips
• DetailHeader title horizontal inset: 64 (clears nav circle buttons)
• Settings sub-item leading indent: 48 — SettingsView

Bucket C — large page-level spacing (28 / 30 / 32 / 40 / 60) across auth/onboarding/hero/empty-state views — untouched.