Add transition prop: CSS shorthand string, web emit, no-op decode elsewhere

[tiensonqin]

Summary

Adds a transition prop so the ~45 transition: declarations currently stranded in logseq's resources/css can migrate onto typed LUI props (logseq refactor/lui work). Follows the additive pattern from #185: schema entry → per-kind admission → Lui_protocol validation → ?transition on every admitted Lui_elements constructor → per-host decode.

The value is the CSS shorthand verbatim — "<property> <duration> [<easing>] [<delay>]", comma-separated list allowed:

Lui_elements.box ~transition:"opacity 0.15s ease" [ ... ]
Lui_elements.text ~transition:"background-color 0.15s ease, border-color 0.15s ease" [ ... ]

• Admission mirrors the hover-*/state-channel table: every kind except root/tooltip/modal surfaces, plus restrictive kbd via its kindProperties entry — 64 constructors get ?transition.
• Validation (Lui_protocol.transition_supported, mirrored in Rust/Swift/Kotlin): each segment needs a CSS <ident> property + 1–2 <time> tokens (s/ms, bare 0 allowed); remaining tokens must be ident or ident(args) (paren-aware tokenizing so cubic-bezier(0.4, 0, 0.2, 1) commas don't split segments). Garbage rejects via the existing Invalid_argument path.
• Web: emits the string literally as transition: — the wire syntax is CSS shorthand.
• gpui: no CSS transition engine and no lerp path for hover/pressed merges, so the value is validated at the wire boundary (P::Transition arm + transition_supported in validation.rs) but intentionally never applied — documented in style.rs.
• apple/android: same admission + validation mirrors, never rendered (state changes apply instantly).
• Regenerated artifacts: lui_protocol.mli, lui_wire_schema.ml, LUIWireSchema.swift, LuiWireSchema.kt, wire_schema.rs, protocol_rules.rs, lui_json_view.ml (?transition auto-decodes from v_str).
• tools/gen_json_view.py: added flex_wrap/list_marker named arg types to the existing no-decoder skip set — the generator was un-runnable since Add CSS-adjacent capability props: sticky, display values, font-family, text-decoration, list-style, flex-wrap, hover fg/border #185 added them; required for regeneration. Both stay view-model-invisible, same as display.

Not included: a transform prop — element transforms need real work on gpui (element vs paint transform), so it stays out per the no-transform-engine rule.

Verified: dune build, dune runtest (107 tests, +transition assertions), node --test tooling/test/*.mjs (8/8), cargo check -p lui-core -p lui-gpui.

Link to Devin session: https://app.devin.ai/sessions/d768c1bf809c48a7a5dffaf7b1370941
Open in Devin Desktop: https://app.devin.ai/desktop/session/d768c1bf809c48a7a5dffaf7b1370941?variant=devin
Requested by: @tiensonqin

[devin-ai-integration]

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