Add M11 polish points: keybinding help labels + action trigger buttons

Bank_panel labels surface each capture action's current key binding
(kbd_getTextFromCmd, unbound-safe); clickable buttons fire the actions
through the existing command-id contract. Pure/shell split noted per point.

PLAN.md

@@ -76,6 +76,20 @@ invariants; drag-out places a valid file in the OS target.
 - [ ] Resample-and-mute-source.
 - [ ] Conform-on-insert (explicit).
 - [ ] Native OS drag-out (deferred final; `InsertMedia` path must already work).
+- [ ] Keybinding help labels: in the docked bank_panel, surface the current key
+  binding for each capture/provenance action (e.g. "Capture Item → <key>") by
+  querying the SDK for the key bound to the action's command id
+  (`kbd_getTextFromCmd(cmd, SectionFromUniqueID(0))` — main section) and formatting
+  a reminder label. Unbound case degrades to the action name with a clear
+  "unbound"/"—" marker (empty/blank return handled explicitly). Split: label-text
+  formatting (binding string + fallback → label) is **pure/testable**; the SDK
+  binding query + label draw is bank_panel shell.
+- [ ] Action trigger buttons: clickable bank_panel buttons that fire the capture and
+  provenance actions directly, routing through the **existing** command-id contract
+  (`Main_OnCommand`/`KBD_OnMainActionEx` with the registered command id — the same id
+  minted at `registerAction`), never re-implementing capture. Split: button
+  hit-testing/layout math is **pure/testable** (mirror of `mode_switch`/`bank_grid`);
+  draw + command dispatch is bank_panel shell.
 
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