feat(webview): surface inline-subtask transitions as distinct chat banners

[easonLiangWorldedtech]

feat(webview): surface inline-subtask transitions as distinct chat banners

Problem

When new_task hits the nesting limit, two things happen that are currently invisible to the user:

1. Auto-flatten: with autoFlattenOnLimit, an over-limit subtask runs inline in the current conversation instead of opening a child tab. The model sees it via the tool result ([auto-flattened: ...]), but the webview renders nothing — tool results are not chat rows.
2. Reject: a nested new_task while an inline phase is already active (or over-limit with auto-flatten off) returns only a tool error, again invisible in the UI.

So "reject create subtask and back to inline mode" had no visual affordance — confirmed by live task 01a00a40, where both the flatten and the reject appeared as plain model text rather than anything the user could recognize at a glance.

Change

Emit two new ClineSay notice types from NewTaskTool and render them as distinct banners:

• inline_subtask_started (auto-flatten) → amber banner, Split icon: "Subtask flattened to inline" + the limit detail.
• inline_subtask_rejected (nested-in-progress / over-limit-reject) → red banner, OctagonX icon: "Nested subtask rejected" + reason.

Both are emitted via task.say(...) in addition to the existing tool result (the model still gets it), so nothing changes for the agent — only the user now sees the transition.

• packages/types: add both to clineSays.
• NewTaskTool.ts: emit in the three non-delegate branches (flatten, reject-nested, reject-limit).
• ChatRow.tsx: two new cases rendering themed banners (VS Code tokens, matching WarningRow styling). Each banner carries a settings hint link that deep-links straight into the task-tree settings (switchTab → settings, values.section = "contextManagement") so the user can adjust maxNestingDepth / autoFlattenOnLimit without hunting for them.
• chatBatchingPredicates.ts: mark both as batching boundaries so they render as their own rows.
• i18n: subtasks.inlineStarted / subtasks.inlineRejected / subtasks.inlineConfigure plus three localized detail strings (inlineStartedDetail, inlineRejectedLimitDetail, inlineRejectedNestedDetail) across all 18 locales.

Also fixed (found while reviewing the live UI)

• Task-tree settings rendered raw i18n keys: ContextManagementSettings referenced settings:taskTree.*, but the translations live under contextManagement.taskTree.*. Corrected all six references; added a regression test asserting the nested path resolves.
• Banner detail text was hardcoded English (e.g. "Nesting limit 2 reached — …"): the say payload is now structured JSON ({ maxDepth } / { reason, maxDepth? }) and the webview renders localized detail strings with interpolation; non-JSON payloads fall back to raw text.

Tests

• Backend (newTaskInlineFlatten.spec.ts): the Task double now carries a say mock; each branch asserts the right say type + message. 6/6 pass.
• Webview (new ChatRow.inline-subtask.spec.tsx): both banners render localized title + detail (both reject reasons covered); the settings-hint link deep-links into the task-tree section on click; unrelated say types render neither. 6/6 pass.
• Settings (ContextManagementSettings.spec.tsx): regression test asserting the nested contextManagement.taskTree.* key path resolves. 36/36 pass.

check-types 11/11. Per-file eslint clean. find-missing-translations.js green across all locales.