feat: smooth terminal reflow on window resize (parity with opencode/Claude Code)

[liw71750-dotcom]

Problem

When resizing the terminal window, the classic CLI (non-TUI, Rich + prompt_toolkit based) does not reflow or re-render the conversation history to fit the new dimensions. This causes multiple visible artifacts:

• Ghost/overlapping lines -- previous content remains at the old width
• Broken table borders -- Rich tables are rendered at the stale width
• Accumulated blank separator lines -- after each resize, extra blank lines pile up
• Distorted scrollback -- when scrolling back through conversation history after a resize, formatting is misaligned
• Status bar duplication -- the prompt/status area can appear as duplicate rows

In contrast, competitor tools handle this smoothly:

• Claude Code -- uses full-screen alternate buffer with SIGWINCH-triggered complete re-render
• Opencode -- recalculates layout on resize events, content reflows seamlessly
• Both give an uninterrupted reading experience regardless of window size changes

Expected Behavior

Resizing the terminal should trigger a complete re-render of the entire conversation history and all active display elements (tables, messages, status bar) to fit the new viewport dimensions -- matching the smooth experience of opencode and Claude Code.

Additional Context

This issue is a tracking feature request that addresses the root cause. There are currently 34+ individual bug reports covering specific manifestations of this problem:

• TUI: Terminal resize accumulates blank separator lines #22976 -- TUI: Terminal resize accumulates blank separator lines
• CLI TUI renders blank lines after terminal resize #17975 -- CLI TUI renders blank lines after terminal resize
• fix(tui): clear terminal on resize to prevent ghost separator lines #23034 -- fix(tui): clear terminal on resize to prevent ghost separator lines
• TUI composer/scrollbar jumps during streaming and terminal resize in Ghostty/Zed #24137 -- TUI composer/scrollbar jumps during streaming and terminal resize
• bug(ui-tui): rapid terminal resize can still leave corrupted glyphs / scattered letters #18449 -- Rapid terminal resize leaves corrupted glyphs
• [Bug]: TUI resize causes ghost copies (same root cause as #5474 but for Ink/TUI) #17961 -- TUI resize causes ghost copies (same root as [Bug]: Terminal resize (SIGWINCH) duplicates status bar and clears response text #5474)
• persistent_output replay strips ANSI/Rich formatting after terminal resize #24017 -- persistent_output replay strips ANSI after resize
• Terminal resize causes status bar duplication and blank line flooding on macOS #19280 -- Status bar duplication and blank line flooding on macOS
• fix(cli): prevent duplicated prompt rows after terminal resize #6766 -- Duplicated prompt rows after resize
• Classic CLI resize clears startup banner/tool summary after terminal maximize #22999 -- Classic CLI resize clears startup banner
• And many more...

A comprehensive reflow solution would resolve all of these individual bugs.

Environment

• macOS 26.4.1
• Terminal: default (also reproduced in various terminal emulators)
• Hermes Agent version: latest (main branch)

Suggested Approach

Investigate implementing a SIGWINCH signal handler that triggers a full re-render of the CLI display buffer, possibly by:

1. Capturing the current conversation state
2. Clearing the screen
3. Re-rendering all content at the new terminal dimensions
4. Preserving scrollback position where possible

For the Ink-based TUI mode (--tui), leverage React's re-render cycle with proper viewport dimensions.

[liw71750-dotcom]

@teknium1 这个问题严重影响日常使用体验。34个issue + 7个零散PR都是打补丁，没有一个从根上解决CLI resize时内容重排的问题。相比opencode和Claude Code的丝滑体验，差距非常明显。

建议把#24164作为P1纳入路线图，一次性把所有resize bug收掉。

#24164