fix(vscode): use a minimum prompt input gutter

[marius-kilocode]

Prompt inputs currently use different horizontal and vertical spacing depending on the host surface. Sidebar chat also had width calculations tied to the older chat gutter, while Agent Manager chat and the New Worktree dialog used separate margin overrides. This makes the same prompt component look misaligned across surfaces and allows zero-margin dialog layouts.

Use one shared --prompt-min-gutter token and derive a responsive --prompt-gutter with max(). The same gutter now controls prompt width, horizontal centering, and vertical spacing in sidebar chat, Agent Manager chat, session-dock states, permission states, and the New Worktree dialog. The dialog keeps its resize and overflow behavior while honoring the minimum. Focused geometry coverage locks the minimum, responsive, and dialog cases.

Before and after comparison:

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (6 files)

• .changeset/prompt-input-minimum-gutter.md
• packages/kilo-vscode/tests/prompt-spacing.spec.ts
• packages/kilo-vscode/webview-ui/agent-manager/agent-manager.css
• packages/kilo-vscode/webview-ui/src/styles/chat-layout.css
• packages/kilo-vscode/webview-ui/src/styles/prompt-input.css
• packages/kilo-vscode/webview-ui/src/styles/session-actions.css

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_{Reviewed by grok-4.6 · Input: 218.1K · Output: 22K · Cached: 1.2M}

_{Review guidance: REVIEW.md from base branch main}

[WebReflection]

love it!