fix(ui): Make read-only content selectable with a Copy context menu (#48)

Root cause: body is user-select: none and each feature had to opt back in; the Markdown preview (and other read-only views) never did, and the app-wide contextmenu guard left no Copy item.
Fix: shared selectableText class (src/ui) for read-only content, and a fallback Copy context menu from browserGuards when right-clicking a selection or a selectable area (component menus still win).
Siblings covered: Quick Documentation / hover / completion docs, hover errors, Quick Definition, debugger value tooltip, inspection messages, message dialogs (no drag on body text), notification titles, About dialog; existing selectable consoles now get Copy too.
Verified in-app on macOS: select in Markdown preview, right-click Copy puts the text on the clipboard; tab context menu unchanged.

Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn

src/features/analysis/InspectionView.tsx

@@ -25,6 +25,7 @@ import {
   type TreeHandle,
   type TreeRowState,
   T,
+  selectableText,
 } from "@/ui";
 import {
   cancelInspection,
@@ -438,7 +439,7 @@ function ProblemDetails({ node, root }: { node: Node | null; root: string }) {
         <Icon name={sev} size={14} className={styles[`sev-${sev}`]} />
         <span>{p.d.source ? `${p.d.source}${p.d.code ? ` (${p.d.code})` : ""}` : <T>Language server</T>}</span>
       </div>
-      <p className={styles.detailsMessage}>{p.d.message}</p>
+      <p className={clsx(styles.detailsMessage, selectableText)}>{p.d.message}</p>
       <div className={styles.muted}>
         {relativeDir(root, p.path) ? `${relativeDir(root, p.path)}/` : ""}
         {basename(p.path)}:{p.d.range.start.line + 1}:{p.d.range.start.col + 1}

src/features/app/AboutDialog.tsx

@@ -3,7 +3,8 @@ import { create } from "zustand";
 import { executeAction } from "@/platform/actions";
 import { t as translate, useT } from "@/platform/i18n";
 import { commands, isTauri, type AppInfo, type BuildInfo } from "@/platform/ipc";
-import { Dialog, IconButton } from "@/ui";
+import clsx from "clsx";
+import { Dialog, IconButton, selectableText } from "@/ui";
 import logo from "../../../src-tauri/icons/128x128.png";
 import { buildInfo, guessOs } from "./host";
 import styles from "./app.module.css";
@@ -82,13 +83,13 @@ function AboutDialog({ onClose }: { onClose: () => void }) {
       <div className={styles.about}>
         <img className={styles.logo} src={logo} alt="" width={64} height={64} />
         <div className={styles.aboutBody}>
-          <div className={styles.productName}>OpenIDEA {build?.version ?? ""}</div>
+          <div className={clsx(styles.productName, selectableText)}>OpenIDEA {build?.version ?? ""}</div>
           {build && (
-            <div className={styles.aboutLine}>
+            <div className={clsx(styles.aboutLine, selectableText)}>
               {t("app.about.build")} #{build.build} ({build.profile})
             </div>
           )}
-          <div className={styles.tagline}>{t("app.about.tagline")}</div>
+          <div className={clsx(styles.tagline, selectableText)}>{t("app.about.tagline")}</div>
           <dl className={styles.facts}>
             {rows
               .filter(([k]) => k !== t("app.about.version") && k !== t("app.about.build"))
@@ -116,12 +117,12 @@ function AboutDialog({ onClose }: { onClose: () => void }) {
               </button>
             )}
           </div>
-          <div className={styles.license}>
+          <div className={clsx(styles.license, selectableText)}>
             {t("app.about.copyright")}
             <br />
             {t("app.about.license")}
           </div>
-          <div className={styles.disclaimer}>
+          <div className={clsx(styles.disclaimer, selectableText)}>
             {t("app.about.thirdParty")} {t("app.about.disclaimer")}
           </div>
         </div>

src/features/debugger/editor/valueTooltip.ts

@@ -9,7 +9,7 @@ import { workflowSettings } from "@/platform/workflowSettings";
 import { activeSession, evaluate } from "../state";
 import { inlineValue } from "../values";
 import { tx } from "@/platform/i18n";
-import { iconMarkup } from "@/ui";
+import { iconMarkup, selectableText } from "@/ui";
 import { mountValueTree } from "../ui/ValueHintTree";
 import styles from "./editor.module.css";
 
@@ -59,7 +59,7 @@ export function valueTooltip(): Extension {
         above: true,
         create: () => {
           const dom = document.createElement("div");
-          dom.className = styles.valueTooltip!;
+          dom.className = `${styles.valueTooltip} ${selectableText}`;
           let tree: { unmount(): void } | null = null;
           if (value.variablesReference > 0) {
             // IDEA's value hint: the "+" expands the object into a variables tree in place.
@@ -73,7 +73,7 @@ export function valueTooltip(): Extension {
             expand.addEventListener("click", () => {
               if (tree) return;
               expand.remove();
-              dom.classList.add(styles.valueTooltipTree!);
+              dom.classList.replace(selectableText, styles.valueTooltipTree!);
               dom.replaceChildren();
               tree = mountValueTree(dom, expr.text, value, session.id);
             });

src/features/viewers/markdown/MarkdownEditor.tsx

@@ -8,7 +8,7 @@ import clsx from "clsx";
 import { call, commands, isTauri } from "@/platform/ipc";
 import { maybeEditorService } from "@/workbench/contributions";
 import { highlightInto } from "@/editor/lsp/markdown";
-import { IconButton } from "@/ui";
+import { IconButton, selectableText } from "@/ui";
 import { useLiveMarkdown } from "./live";
 import { modeOf, useMarkdownModes } from "./modes";
 import { ANCHOR_PREFIX, previewOffsetForLine, renderMarkdown, resolveLink, slugify } from "./render";
@@ -140,7 +140,7 @@ function MarkdownPreview({ path, sync }: { path: string; sync: boolean }) {
   return (
     <div
       ref={ref}
-      className={styles.preview}
+      className={clsx(styles.preview, selectableText)}
       tabIndex={-1}
       role="document"
       aria-label="Markdown preview"