Kata Shell 0.9.0

First public pre-release of Kata Shell, a native macOS file manager (AppKit + SwiftUI).

• Directory tree with Favorites panel, pin-as-root scoping, and keyboard navigation.
• Tabbed content view with Table and Preview modes, cloneable tabs, and per-tab UI state
  (scroll positions, column widths, preview zoom) restored on every tab switch.
• Full file operations: create, rename, delete, multi-select, copy/cut/paste with real
  clipboard interop with Finder in both directions.
• Embedded terminal (PTY-backed zsh) with live working-directory tracking in the address bar.
• Markdown/text editor with Edit and Preview modes, F3/F4 open-and-toggle, and Esc-to-close.
• Context-sensitive ribbon with content zoom, configurable placement and button appearance.
• Settings: date format, table columns, file-preview extensions, tree navigation mode, and
  per-surface font choices including the bundled JetBrains Mono.

Known limitation: this pre-release is ad-hoc signed (no Apple Developer ID configured yet). On first launch, macOS Gatekeeper requires right-click → Open, or System Settings → Privacy &
Security → Open Anyway. Public downloads will be Developer ID signed and notarized starting
with the first release built via Tools/Release/release.sh (still within the 0.9.x pre-release series — see Doc/Dev/01_DEPLOYMENT.md); version 1.0.0 is reserved for the end of the early-access period, not for signing/notarization.