feat(cli): Prioritize shallow subfolders when scanning for completer

[hongquan]

Related Issue

Resolve #1276

Description

Collect files and save to a trie data structure as pool for autocomplete source.

Checklist

• I have read the CONTRIBUTING document.
• I have linked the related issue, if any.
• I have added tests that prove my fix is effective or that my feature works.
• I have run make gen-changelog to update the changelog.
• I have run make gen-docs to update the user documentation.

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[Copilot]

Pull request overview

This PR addresses issue #1276 by changing how the shell @ file mention completer collects and orders workspace paths so that shallow paths are prioritized and deeper paths can be expanded incrementally.

Changes:

• Add a trie-based path collector (PathTrie) that scans directories in BFS order with incremental depth expansion.
• Update the shell @ completer to use PathTrie and cache results keyed by the current fragment.
• Add unit tests for PathTrie behavior and update changelogs/docs entries.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/kimi_cli/utils/path.py	Introduces PathTrie/PathTrieNode with BFS, staged collection, and directory lookup for formatting.
src/kimi_cli/ui/shell/prompt.py	Switches local file mention completion from os.walk to PathTrie, adds fragment-aware caching and directory formatting.
tests/ui_and_conv/test_path_trie.py	Adds tests for trie node behavior, BFS ordering, incremental depth expansion, and limit handling.
CHANGELOG.md	Notes the shell completion fix in Unreleased.
docs/en/release-notes/changelog.md	Mirrors changelog entry for English docs.
docs/zh/release-notes/changelog.md	Mirrors changelog entry for Chinese docs.
docs/en/configuration/config-files.md	Adjusts the H1 casing.
pyproject.toml	Re-formats/re-orders configuration blocks without apparent semantic changes.

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[Copilot]

This page’s top-level heading was changed to sentence case (# Config files), but other pages in this same section use title case (e.g. # Data Locations, # Environment Variables). If the docs convention is title case for H1s, consider keeping # Config Files for consistency.

Suggested change

	# Config files
	# Config Files

[hongquan]

This change is caused by make gen-docs.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

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