feat(tui): add ctrl+r history search

[jiahaoxiang2000]

Summary

Implements Ctrl+R history search functionality for the TUI prompt, allowing users to fuzzy search through their prompt history.

Changes

• Added DialogHistorySearch component with fuzzy filtering and deduplication
• Increased max history entries from 50 to 100
• Added items getter and reset() method to PromptHistory context
• Added history_search keybind (default: ctrl+r) to config
• Integrated history search into prompt component

Closes https://github.com/sst/opencode/issues/5062 Related #6276

[edlsh]

Hey @jiahaoxiang2000! I implemented an alternative approach in #6276 that uses inline reverse-i-search (bash-style) instead of a modal dialog.

Key differences:

• Matches display directly in the prompt textarea rather than a separate dialog
• Follows the exact bash/zsh/fish convention: (reverse-i-search)'query': N/M
• Reuses existing prompt rendering for parts/extmarks instead of creating a separate list view

This was inspired by @ShpetimA's suggestion in #5062:

Maybe just simple search style like bash where you search and it shows on the input instantly instead of opening history modal.

Both approaches have merit - the modal provides a visual list which some users might prefer, while inline keeps the shell-like feel. Curious what the maintainers think about which direction fits better for opencode's TUI!