composer: build on Lui_element_combine.composer

[tiensonqin]

Summary

view_composer.ml now delegates the capsule layout to Lui_element_combine.composer / composer_collapsed instead of hand-rolling it. Identical UI/UX: same accessibility identifiers (surface.composer.root, field.composer, row.composer.controls, spacer.composer.*, button.send, button.composer.expand), same per-host variants (Flutter: surface-container-high capsule + 48pt primary send icon + secondary collapsed "Capture a thought"; Apple: glass capsule + black circular arrow-up send), same behavior (attachment strip gated by assets signal, autofocus signal, FocusComposer capsule press, SendComposer on send/submit, ExpandComposer on collapsed press).

Chat-specific content is passed through the generic params: ~actions carries the attachment and task-status buttons (with their picker stacks), ~attachments/~attachments_visible carry the asset strip, ~send_icon selects app "send"/app "arrow-up" per platform.

Bumps the lui pin to e5f940a (the combine-composer branch on logseq/lui, PR #55). Once that PR lands, the pin should move to the merged main sha.

Deleted now-duplicated helpers: with_press, *_composer_send_button, collapsed_composer_button (mli pruned accordingly).

Verified: dune build @shared/native/runtest — 718 tests pass, including the composer layout/parity assertions.

Link to Devin session: https://app.devin.ai/sessions/7430d12bacc441448cf27425a36090a4
Open in Devin Desktop: https://app.devin.ai/desktop/session/7430d12bacc441448cf27425a36090a4?variant=devin
Requested by: @tiensonqin

[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]

Verified the Lui_element_combine.composer migration on a real iPhone 17 simulator (iOS 27.0) — built the chat app from this branch, signed in, created a sync graph against local db-sync, and exercised the composer end-to-end:

• ✅ Collapsed "Capture" capsule renders; tapping expands to text field + + attach + task-status + greyed send
• ✅ Send button transitions grey → solid black once text is typed
• ✅ Send clears the field and appends the block to today's journal
• ✅ Draft survives collapse → re-expand
• ✅ Attachment menu (File/Camera/Photo/Audio) and task-status picker (6 statuses) both open and respond