combine: add Menu action variant to buttons

[RCmerci]

Summary

Lui_element_combine.buttons actions are now polymorphic: Press (existing behavior) or Menu (press-to-open native dropdown). This is a breaking change to the young action record — callers wrap their record in Press (gallery and tests updated here; the journal V.buttons wrapper gets a matching wrap in its own PR).

type action =
  | Press of { label : string; icon : icon; text : string option; on_press : Lui_protocol.event -> unit }
  | Menu of { label : string; icon : icon; text : string option; menu : t list; on_dismiss : (Lui_protocol.event -> unit) option }

A Menu action mounts a menu_trigger + dropdown_menu inside a sizing cell (box ~height:44, icon-only → ~width:44) rather than in a bare button_group slot. MenuTrigger carries no surface properties in the wire protocol, so the capsule chrome (glass background, 999 corner radius) lives on the wrapping cell — no wire whitelist or schema changes needed; style-class was already supported on MenuTrigger.

Hit area: the trigger gets style_class:"capsule", which LUIMenuTriggerView uses to stretch its label to the full cell frame with .contentShape(Rectangle()) (same pattern as the PR #56 toolbar hit fix): icon-only cells greedy-fill the pinned 44×44 frame; text cells greedy-fill height and take 12pt horizontal padding inside the hit region.

buttons semantics unchanged: [] → invalid_arg; a single action (press or menu) gets its own glass capsule; multiple share a button_group capsule.

Gallery ("Glass Buttons" section) demos a standalone icon-only menu action and a fused press+menu capsule.

Caveat

Inside a hoisted toolbar capsule segment (ControlGroup), a Menu action renders a native Menu — it stays tappable but does not get the fused ControlGroup styling that Button members get. Acceptable for now since buttons isn't used there yet.

Verification

• dune build + dune runtest: 29 tests pass, incl. new menu action test (single capsule → MenuTrigger → DropdownMenu → MenuItem; menu-item press dispatches its handler; group has Button + Box cells).
• swift build --package-path platform/apple: clean.
• iOS simulator evidence on the LUI gallery app: recorded separately in the session (menu opens on capsule tap incl. off-glyph area, item press fires handler, fused mixed capsule).

Link to Devin session: https://app.devin.ai/sessions/3bce435625ba4bc086c09520e0920db5
Open in Devin Desktop: https://app.devin.ai/desktop/session/3bce435625ba4bc086c09520e0920db5?variant=devin
Requested by: @RCmerci

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring

[devin-ai-integration]

iOS simulator verification — Menu action in Lui_element_combine.buttons ✅

Verified on iPhone 17 sim (iOS 27.0) in the LUIComponents gallery "Glass Buttons" section, driving real taps on the Simulator window with simctl io screenshots as pixel evidence.

• Standalone icon-only menu capsule → native dropdown opens with Duplicate/Rename/Archive; "Rename" → trailing paragraph shows "Context action: Rename"
• Off-glyph tap inside capsule bounds still opens the menu (capsule contentShape hit region works)
• Mixed press+menu capsule renders fused; ellipsis half opens the menu ("Duplicate" → "Context action: Duplicate"), plus half fires press ("Context action: New note")

Full annotated recording: /Users/devin/screencasts/rec-2c51cc96-1476-4132-9711-3d1540bc23de/rec-2c51cc96-1476-4132-9711-3d1540bc23de-edited.mp4

[devin-ai-integration]

Icon-size fix (83bcb3a) verified on iOS sim ✅

LUIMenuTriggerView's LUIIconImage is .resizable() — unlike every other call site it had no frame constraint, so the glyph expanded to fill the 44pt capsule cell. Now constrained to LUIButtonVisualPolicy.iconExtent (~18pt), matching sibling buttons:

• Gallery: standalone "…" capsule and mixed "+"+"…" capsule both show matching icon extents; menu still opens and "Rename" fires → "Context action: Rename"
• Journal: account capsule person icon normal size next to info capsule; menu opens with all 5 items