feat(config): add hotbar slot persistence

Add durable [[hotbar]] config bindings for slots 1-8, including default
  bindings when no hotbar config is present.

  Validate bindings without panicking: skip out-of-range slots, use the last
  duplicate slot, and preserve unknown actions so future UI layers can show
  disabled placeholders.

config.example.toml

@@ -88,6 +88,26 @@ cost_currency = "usd" # usd | cny
 check_for_updates = true
 # update_uri = "https://internal.mirror.example/codewhale/releases/latest"
 
+# ─────────────────────────────────────────────────────────────────────────────────
+# Hotbar slots (#2061 / #2064)
+# ─────────────────────────────────────────────────────────────────────────────────
+# Optional 1-8 sidebar hotbar bindings. When no [[hotbar]] tables are present,
+# the TUI uses built-in defaults:
+#   1 voice.toggle      2 session.compact   3 mode.plan        4 mode.agent
+#   5 mode.yolo         6 palette.open      7 sidebar.toggle   8 trust.toggle
+#
+# Invalid slots are skipped with a warning, duplicate slots use the last entry,
+# and unknown actions are preserved so the UI can show a disabled placeholder.
+#
+# [[hotbar]]
+# slot = 1
+# label = "voice"
+# action = "voice.toggle"
+#
+# [[hotbar]]
+# slot = 2
+# action = "session.compact"
+
 # ─────────────────────────────────────────────────────────────────────────────────
 # Paths
 # ─────────────────────────────────────────────────────────────────────────────────