fix(workbench): 优化侧栏悬停、选中和提示框样式 (#2094)

Sidebar buttons used a larger radius than the rest of the IDE, and their tooltips opened below the button, often over neighbouring stripe buttons.

Stripe buttons now use a 6px radius, and their tooltips open toward the inside of the window, with a dark background in light themes.

Siblings covered: every theme and plugin theme falls back to its base tooltip tokens, long tooltips flip correctly at the window edge, the shortcut hint stays readable, and the More button gets the same tooltip.

Co-authored-by: PLZY <[email protected]>

docs/plugins/themes.md

@@ -103,6 +103,10 @@ Three things still layer on top of it:
 The selection is remembered. When the plugin is disabled or uninstalled the
 built-in theme returns.
 
+Stripe tooltips use `--bg-stripe-tooltip`, `--fg-stripe-tooltip`,
+`--border-stripe-tooltip` and `--shadow-stripe-tooltip`. A plugin that omits
+these tokens inherits its corresponding base tooltip tokens, including in light themes.
+
 ## Building, packaging, installing
 
 There is no build step. The package *is* the folder.
@@ -324,7 +328,7 @@ a token.
 
 <!-- BEGIN GENERATED TOKEN REFERENCE: pnpm gen:theme-docs -->
 
-243 themeable tokens: 121 in the UI theme file, 122 in the editor colour scheme file.
+247 themeable tokens: 125 in the UI theme file, 122 in the editor colour scheme file.
 
 ### Surfaces (UI theme)
 
@@ -571,6 +575,10 @@ a token.
 
 | Token | Islands Dark | Islands Light |
 |---|---|---|
+| `--bg-stripe-tooltip` | `var(--bg-tooltip)` | `#27282e` |
+| `--fg-stripe-tooltip` | `var(--fg-tooltip)` | `#ffffff` |
+| `--border-stripe-tooltip` | `var(--border-tooltip)` | `#383a42` |
+| `--shadow-stripe-tooltip` | `var(--shadow-tooltip)` | `0 2px 8px rgba(0, 0, 0, 0.24)` |
 | `--bg-tooltip` | `#33353b` | `#ffffff` |
 | `--fg-tooltip` | `#d1d3d9` | `#000000` |
 | `--border-tooltip` | `#33353b` | `#d1d3d9` |