Fix the dead win7 context menu, flatten the selection, add a tab menu

Right-click did nothing under the win7 skin, and then swallowed the next
click. 7.css declares `position: relative` on ul[role=menu] and the `skin`
layer outranks `utilities`, so Tailwind's `.fixed` lost: [style.left/top.px]
became flow offsets from the menu's static position — the last child of the
h-screen frame — and every menu rendered below the viewport, unreachable
behind overflow:hidden. Its backdrop is a plain <div>, unmatched by 7.css, so
that stayed genuinely fixed and ate the following click. Regressed in 0ae2a62,
when the menu adopted 7.css's real markup.

Restated `position: fixed` in skinfix, scoped to a new `w7-ctx` marker so
7.css's own menus keep theirs. scripts/menu-probe.ts is the regression test:
it renders the menu at declared coordinates, pixel-scans whether it landed
there, and carries a marker-less control menu (the bug verbatim) as its own
discriminator. A resting pixel diff cannot see this class of bug.

Selection band goes flat: --w7-sel-bg/-bd (#cbe8f6/#26a0da) is what Explorer
actually painted, where 7.css reused --w7-el-grad-h, its Aero element-hover
ramp. That var is left alone — buttons and tabs still want the gloss. The
unfocused pane gets the grey idle band; the band still never disappears with
focus, it only weakens. Harness diff confirms the change touches selection
rows and nothing else, in both themes.

New workspace-tab right-click menu in both skins: New Tab, Close Tab, Close
Other Tabs, Close Tabs to the Right, Disconnect. The target id travels inside
the action string because the right-clicked tab is not necessarily the active
one. Illegal entries are disabled rather than omitted, the way Win7 greyed
out — and since 7.css's [aria-disabled] handling is CSS-only, the keyboard
paths check the flag themselves.

Co-Authored-By: Claude <noreply@anthropic.com>

docs/architecture.md

@@ -256,18 +256,29 @@ one look → that skin's folder; tokens both skins consume → `ui/src/styles.cs
   boot and on the `settingsChanged` broadcast (so editor/manager windows follow).
 - `file-actions.service.ts` — toolbar/keyboard/context-menu file ops, always
   against an explicit panel; `menuTarget` remembers the right-clicked row.
-- `context-menu.service.ts` + `context-menu.ts` — the panel right-click menus,
-  in HTML. Electrobun's native `showContextMenu` is a no-op on Linux, so it was
+- `context-menu.service.ts` + `context-menu.ts` — the panel and tab right-click
+  menus, in HTML. Electrobun's native `showContextMenu` is a no-op on Linux, so it was
   retired on ALL platforms rather than kept as a second code path (see
   platform-notes.md). The service builds the item list (row / empty-space menu,
   and the header column picker) and holds the open request as a signal; the
   component renders it at the pointer with edge-flip clamping, arrow/Enter/Escape
   keys, and close-on-blur/resize/scroll. Picked items are emitted verbatim as
-  `ctx-*` / `col:*` strings through `RpcService.emitMenuAction`, so they land in
-  the SAME `App.handleMenuAction` dispatcher the macOS app menubar uses — one
-  handler, two sources. The three shell actions the webview cannot perform
+  `ctx-*` / `col:*` / `tab:*` strings through `RpcService.emitMenuAction`, so they
+  land in the SAME `App.handleMenuAction` dispatcher the macOS app menubar uses —
+  one handler, two sources. The three shell actions the webview cannot perform
   (reveal, open-with-default, copy path) go back to bun via the `shellItemAction`
   RPC, which is all that remains of the old native menu.
+  `tabItems()` builds the workspace-tab menu (`tab:new`, and
+  `tab:close|close-others|close-right|disconnect:<id>`), served by
+  `PanelsService.closeOtherWorkspaces` / `closeWorkspacesToRight` /
+  `disconnectWorkspace`. **The target id travels inside the action string**: the
+  right-clicked tab is not necessarily the active one, so nothing on that path
+  may fall back to `activeWorkspaceId`. Illegal entries are `disabled`, not
+  omitted — Win7 greys out, and a menu whose items move between right-clicks is
+  worse than one with a dead row. 7.css hangs that state on
+  `li[role=menuitem][aria-disabled]` (opacity + `pointer-events: none`), which
+  the keyboard path never consults — so `pick()` and the arrow-key walker check
+  the flag themselves, in both skins.
 - `file-icons.ts` — extension → category map driving glyphs, colors
   (fixed `--icon-*` tokens, never accent-tinted) and the Kind column.
 - `platform.ts` — preload-global readers (`PLATFORM`, `APP_MODE`,
@@ -417,6 +428,14 @@ zeroed); the frame reads the state off its own child with
 `:has(> .title-bar.is-maximized)`, which `title-bar.ts` publishes from its
 existing `maximized` signal rather than subscribing to `windowState` twice.
 
+**Selection band**: the file list's selected row is a FLAT Win7-Explorer blue
+(`--w7-sel-bg/-bd` = `#cbe8f6`/`#26a0da`), not 7.css's `--w7-el-grad-h` — that
+var is its Aero element-hover ramp and stays reserved for buttons and tabs,
+which still want the gloss. The unfocused pane gets `--w7-sel-bg-idle/-bd-idle`,
+Explorer's grey inactive selection; the band never disappears with focus, only
+weakens (the commander convention above). All four are dark-overridden in BOTH
+dark blocks.
+
 **Context menu**: pure 7.css via its real menu contract —
 `ul[role=menu] > li[role=menuitem] > button` for actions,
 `input[type=checkbox] + label` for the checkable column toggles, dividers as
@@ -426,7 +445,10 @@ nothing, and wrongly concluded "7.css has no menu component" — it has a full
 one (`dist/gui/menu.css`), including the gutter stripe, disabled state and
 submenu arrows. Keyboard moves REAL focus between items (7.css styles
 `:focus-visible` like `:hover`); Enter/Space activate buttons natively. Only
-menu.css's hardcoded light literals are restated for dark, in `skinfix`.
+menu.css's hardcoded light literals are restated for dark, in `skinfix` — plus
+one structural override: `.w7-ctx` restores `position: fixed`, which 7.css's own
+`position: relative` on `ul[role=menu]` had been silently winning (see
+gotchas.md; `scripts/menu-probe.ts` is the regression test).
 
 **Font**: Segoe UI is absent off Windows and not redistributable. Noto Sans —
 the substitute 7.css itself names — is vendored (OFL-1.1, from