refactor(capture): expose offline tail as docked-panel toggle

Replace the ...-with-tail variant actions with a pure tail_control module +
a docked-panel footer toggle (Off/Auto/Manual) read by CAPTURE_ITEM/TRACK.
Default None (byte-identical); Manual fixed 2s, in-memory session lifetime.
Tail mechanism unchanged; retired the variant ids.

src/render_settings.h

@@ -89,7 +89,7 @@ double autoTrimEndRatio();
 //   None   — exact bounds, no tail. Byte-identical to the pre-tail capture. The
 //            default and the ONLY mode for null-test / verify captures.
 //   Auto   — generous 8 s tail then trim trailing silence to -72 dB (surgical
-//            normalize). The user-facing "…with tail" default.
+//            normalize). The user-facing tail-on option (panel toggle).
 //   Manual — a fixed tail length (clamped to the 8 s cap), no trim.
 enum class TailMode {
     None,
@@ -213,13 +213,11 @@ RazorRange razorUnionBounds(const std::vector<RazorRange>& ranges);
 
 // --- Capture-action taxonomy (the bindable set main.cpp registers) -----------
 //
-// One row per bindable SCOPE action. Two scopes (item / track), each in two tail
-// variants: an exact-bounds row (TailMode::None) and a paired "…with tail" row
-// (TailMode::Auto). The range each captures (razor-else-time) is inferred at fire
-// time, not a mode. The tail variants are additive — the None rows keep their
-// documented exact-bounds contract byte-for-byte; the Auto variants are a separate
-// opt-in action rather than a silent default flip (Daniel's lean, spec §Open
-// questions). Bounded, discoverable, NO dialogs (the tool's no-clutter ethos).
+// One row per bindable SCOPE action: item and track. The range each captures
+// (razor-else-time) is inferred at fire time, not a mode. TAIL is NOT a per-action
+// variant — the tail MODE (None/Auto/Manual) is a panel SETTING the capture reads
+// at fire time (see tail_control + bank_panel), so a single pair of actions covers
+// every tail state. Bounded, discoverable, NO dialogs (the tool's no-clutter ethos).
 //
 // commandString is FOREVER-STABLE (user keybindings key off it) — never change a
 // shipped value. baseName feeds the file stem (sanitized by capture_paths).
@@ -228,17 +226,16 @@ struct CaptureActionDef {
     const char*  description;    // Actions-list label
     const char*  baseName;       // file-stem base for this capture
     CaptureScope scope;          // FX scope (item / track)
-    TailMode     tailMode;       // None (exact bounds) or Auto ("…with tail")
 };
 
 // The capture-action table. Iterated by main.cpp to register the family and route
 // each fired command back to its definition. Kept here (pure) so the taxonomy is
 // one testable list, not scattered registration code.
 //
-// Four rows: CAPTURE_ITEM / CAPTURE_TRACK (exact bounds, TailMode::None) plus the
-// paired CAPTURE_ITEM_TAIL / CAPTURE_TRACK_TAIL variants (TailMode::Auto). There is
-// no master capture — to capture the master you render a track. Razor is an inferred
-// range, not a mode, and each scope enforces its FX-scope invariant via fxBypassPlanFor.
+// Two rows: CAPTURE_ITEM / CAPTURE_TRACK. There is no master capture — to capture
+// the master you render a track. Razor is an inferred range, not a mode, and each
+// scope enforces its FX-scope invariant via fxBypassPlanFor. The tail mode each
+// capture applies is read from the docked-panel setting, not baked into the row.
 const std::vector<CaptureActionDef>& captureActionTable();
 
 } // namespace reasampler