feat: Expand hook system to handle simple exec and plugin extensibility.

Item Model Expansion - Item now caches sublabel, icon, group with accessors. Added resolve_field_path() for dotted path traversal and field_value() on Item.
Output Struct - New OutputItem with OutputAction (select/cancel) and index. Object values flatten, strings get a value field. MenuResult::Selected now carries { value, index }.
Hook Types - Replaced the old Hook trait with HookEvent (serializable, 6 variants), HookResponse (deserializable, 5 commands), HookHandler trait (sync for dyn-compatibility), and parse_hook_response() with tracing warnings.
New Actions & Menu Methods - Added ReplaceItems, RemoveItems, ProcessHookResponse, CloseMenu actions. Menu trait gained original_index(), replace_all(), remove_by_indices(), formatted_label(). Pipeline got rebuild() and rebuild_with_values(). Smart cursor preservation on replace.
Lifecycle Events - MenuRunner emits Open, Close, Hover, Select, Cancel, Filter events through the dispatcher. Cursor tracking for Hover detection.
Debounce - DebouncedDispatcher with 4 modes: None, Debounce, CancelStale, DebounceAndCancelStale. Defaults: hover=DebounceAndCancelStale(200ms), filter=Debounce(200ms).
Exec Hooks - ShellExecHandler maps --on-{open,close,hover,select,cancel,filter}-exec flags to fire-and-forget subprocesses. Event JSON piped to stdin.
Handler Hooks - ShellHandlerHook launches persistent processes per --on-{event} flag. Bidirectional JSON lines: events on stdin, responses on stdout flowing back through Action::ProcessHookResponse. CompositeHookHandler dispatches to both.
--filter-fields - --filter-fields label,sublabel,meta.tags searches multiple fields. Combined text for fuzzy, individual for exact/regex.
--format - FormatTemplate parses {field.path} placeholders. --format '{label} - {sublabel}' controls display. TUI renders formatted_text when available.
Field Filters - meta.res:3840 in query syntax matches specific fields. !meta.res:3840 for inverse. Pipeline stores item Values for field resolution. Requires dotted path (single word colons stay fuzzy).

README.md

@@ -105,16 +105,28 @@ cargo test --workspace
 Requires Rust stable. The repo includes a `rust-toolchain.toml` that
 pins the version and pulls in rust-analyzer + clippy.
 
+## Current Status
+
+Phases 1 through 3 are complete. pikl works as a TUI menu with:
+- Fuzzy, exact, regex, and inverse filtering with `|` pipeline chaining
+- Vim navigation (j/k, gg/G, Ctrl+D/U, Ctrl+F/B, modes)
+- Structured JSON I/O with sublabel, icon, group, and arbitrary metadata
+- Lifecycle hooks: exec (fire-and-forget) and handler (bidirectional)
+- Debounce and cancel-stale for rapid events
+- Format templates (`--format '{label} - {sublabel}'`)
+- Field-scoped filtering (`--filter-fields`, `meta.res:3840` syntax)
+- Headless scripting via `--action-fd`
+
 ## Platform Support
 
 | Platform | Frontend | Status |
 |---|---|---|
 | Linux (Wayland) | GUI (layer-shell overlay) | Planned |
 | Linux (X11) | GUI | Planned |
-| Linux | TUI | Planned |
+| Linux | TUI | Working |
 | macOS | GUI | Planned |
-| macOS | TUI | Planned |
-| Window | GUI | Low Priority |
+| macOS | TUI | Working |
+| Windows | GUI | Low Priority |
 
 ## License