feat: add per-mapping --allow-fallback for layout-independent shortcuts

Add --allow-fallback option to the map command that controls shifted
and ascii (alternate_key) fallback for individual key mappings.

For non-Latin keyboard layouts, when the current layout key is
non-ascii (codepoint > 127 and < 0xE000), the alternate_key from
the base layout is used for matching if the mapping opts in via
--allow-fallback=shifted,ascii.

Default kitty bindings use --allow-fallback=shifted,ascii so they
work out of the box with non-Latin layouts. User custom mappings
default to --allow-fallback=shifted (preserving existing shifted_key
behavior without ascii fallback).

--allow-fallback=none disables all fallback for a mapping.

Python side: parse_options_for_map() in options/utils.py handles flag
parsing, ShortcutMapping uses it in __init__. get_shortcut() filters
candidates by per-mapping allow_fallback.

Go side: ParseMap() handles --allow-fallback, KeyAction stores
AllowFallback, ShortcutTracker.Match passes it to matching.
MatchesParsedShortcut defaults to shifted,ascii for hardcoded shortcuts.

Migrated kittens (themes, command_palette, diff, choose_files) to
use ShortcutTracker with configurable map entries.

Tests added for Python (5 test methods) and Go (ParseMap + key matching).

kittens/command_palette/main.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/kovidgoyal/kitty/tools/cli"
+	"github.com/kovidgoyal/kitty/tools/config"
 	"github.com/kovidgoyal/kitty/tools/tty"
 	"github.com/kovidgoyal/kitty/tools/tui"
 	"github.com/kovidgoyal/kitty/tools/tui/loop"
@@ -256,21 +257,23 @@ type CachedSettings struct {
 }
 
 type Handler struct {
-	lp              *loop.Loop
-	screen_size     loop.ScreenSize
-	all_items       []DisplayItem
-	filtered_idx    []int       // indices into all_items for current results
-	match_infos     []matchInfo // parallel to filtered_idx, valid when query != ""
-	query           string
-	selected_idx    int
-	scroll_offset   int
-	input_data      InputData
-	result          string // action definition to execute after exit
-	display_lines   []displayLine
-	results_start_y int
-	results_height  int
-	show_unmapped   bool
-	cv              *utils.CachedValues[*CachedSettings]
+	lp                 *loop.Loop
+	screen_size        loop.ScreenSize
+	all_items          []DisplayItem
+	filtered_idx       []int       // indices into all_items for current results
+	match_infos        []matchInfo // parallel to filtered_idx, valid when query != ""
+	query              string
+	selected_idx       int
+	scroll_offset      int
+	input_data         InputData
+	result             string // action definition to execute after exit
+	display_lines      []displayLine
+	results_start_y    int
+	results_height     int
+	show_unmapped      bool
+	cv                 *utils.CachedValues[*CachedSettings]
+	shortcut_tracker   config.ShortcutTracker
+	keyboard_shortcuts []*config.KeyAction
 }
 
 func (h *Handler) initialize() (string, error) {
@@ -290,6 +293,8 @@ func (h *Handler) initialize() (string, error) {
 	settings := h.cv.Load()
 	h.show_unmapped = settings.ShowUnmapped
 
+	h.keyboard_shortcuts = config.ResolveShortcuts(NewConfig().KeyboardShortcuts)
+
 	if err := h.loadData(); err != nil {
 		return "", err
 	}
@@ -852,16 +857,27 @@ func (h *Handler) onKeyEvent(ev *loop.KeyEvent) error {
 		h.triggerSelected()
 		return nil
 	}
-	if ev.MatchesPressOrRepeat("up") || ev.MatchesPressOrRepeat("ctrl+k") || ev.MatchesPressOrRepeat("ctrl+p") {
+	if ev.MatchesPressOrRepeat("up") {
 		ev.Handled = true
 		h.moveSelection(-1)
 		return nil
 	}
-	if ev.MatchesPressOrRepeat("down") || ev.MatchesPressOrRepeat("ctrl+j") || ev.MatchesPressOrRepeat("ctrl+n") {
+	if ev.MatchesPressOrRepeat("down") {
 		ev.Handled = true
 		h.moveSelection(1)
 		return nil
 	}
+	if ac := h.shortcut_tracker.Match(ev, h.keyboard_shortcuts); ac != nil {
+		ev.Handled = true
+		switch ac.Name {
+		case "selection_up":
+			h.moveSelection(-1)
+		case "selection_down":
+			h.moveSelection(1)
+		}
+		return nil
+	}
+
 	if ev.MatchesPressOrRepeat("page_up") {
 		ev.Handled = true
 		delta := max(1, int(h.screen_size.HeightCells)-4)

kittens/command_palette/main.py

@@ -6,11 +6,38 @@ import sys
 from functools import partial
 from typing import Any
 
+from kitty.conf.types import Definition
 from kitty.fast_data_types import add_timer, get_boss
 from kitty.typing_compat import BossType
 
 from ..tui.handler import result_handler
 
+definition = Definition(
+    '!kittens.command_palette',
+)
+
+agr = definition.add_group
+egr = definition.end_group
+map = definition.add_map
+
+# shortcuts {{{
+agr('shortcuts', 'Keyboard shortcuts')
+
+map('Move selection up',
+    'selection_up --allow-fallback=shifted,ascii ctrl+k selection_up',
+    )
+map('Move selection up',
+    'selection_up --allow-fallback=shifted,ascii ctrl+p selection_up',
+    )
+map('Move selection down',
+    'selection_down --allow-fallback=shifted,ascii ctrl+j selection_down',
+    )
+map('Move selection down',
+    'selection_down --allow-fallback=shifted,ascii ctrl+n selection_down',
+    )
+
+egr()  # }}}
+
 
 def collect_keys_data(opts: Any) -> dict[str, Any]:
     """Collect all keybinding data from options into a JSON-serializable dict."""
@@ -188,3 +215,5 @@ elif __name__ == '__doc__':
     cd['options'] = OPTIONS
     cd['help_text'] = help_text
     cd['short_desc'] = help_text
+elif __name__ == '__conf__':
+    sys.options_definition = definition  # type: ignore