fix(harmonyos): unify conversation chrome and restore dual-fold master-detail

[wgqqqqq]

Summary

• Name the two HarmonyOS surfaces 本地 / 远程, drop the empty-home suggestion chips, and make thinking blocks show running vs done without leftover chrome.
• Let local chat send images for real (Anthropic/OpenAI multimodal payloads), instead of hiding the plus button or throwing imageNotSupported.
• Fix the connect sheet: unsigned-in first open lands on the explainer, scan is a first-class action on the signed-in device list, a cloud session skips the account-auth password prompt, pairing progress stays on the sheet until success, switching to 远程 no longer auto-opens the sheet, and a scanned URL connects once.
• Unify conversation chrome onto one header and one ConversationView (create included), move presentation DTOs into pages/state/, and split ConversationController by local/remote/shared intent.
• Compact remote home shows a disconnected state unless the transport is actually connected; profile device rows can reconnect the last target or select an online desktop.
• Unfolded dual-fold uses crease-aligned master-detail (expanded foldable still goes wide if crease data is missing). Folded stays compact. File preview on one crease splits on that crease. No third conversation column on tri-fold.

HarmonyOS-only. Stacked on the conversation/session work in #2214; no Android/Kotlin client.

Test plan

• LocalTest (entry@default, ohos.test.type=LocalTest) — 299/299
• assembleHap for entry@default
• On device: switch 本地 / 远程 without the connect sheet opening; Remote Home 连接 still opens it
• Unsigned-in connect sheet opens on the pair-code explainer, not the camera; 我有配对码 opens the scanner
• Signed-in device list shows 扫描二维码连接 without expanding 其他连接方式
• While already signed into BitFun cloud, scanning a same-account QR does not ask for the password again
• Pairing status stays on the sheet through parsing/pairing; sheet closes and Remote Home appears only after success
• Local chat plus button picks images and a multimodal send reaches the model
• Compact remote home after desktop drop shows connect, not 「选择一个会话」
• Profile 设备管理 shows 连接 for the last target / online desktops
• Mate X7 unfolded (2210×2416): 本地/远程 master on the left, composer on the right screen
• Folded compact still uses the drawer; tri-fold two-crease device still unverified