feat: add copy and truncation controls to tool call cards - #38

Tool call cards now have a Copy button on each expanded section and truncate long text behind a Show more toggle. Previously the full text always rendered in place and there was no quick way to reuse it.

Part of #2
Closes #37

What changed:

• Each Input and Output section in WorkbenchControls.tsx gets a Copy button that writes the exact section text to the clipboard and shows Copied for a short confirmation. The copied text is the same text the card displays, including the No input, No output, and Waiting for output fallbacks.
• Section text over 2000 characters (TOOL_TEXT_PREVIEW_LIMIT) renders only the first 2000 characters with a Show more button. Show more reveals the full text and switches to Show less, which truncates again. Header summary, Running, Done, and Failed states, and collapsed-by-default behaviour are unchanged.

Verified:

• bun install --frozen-lockfile passed
• bun run lint passed, 0 warnings and 0 errors
• bun run typecheck passed across renderer, main, and preload configs
• bun run test:unit passed, 71 tests
• bun run test:integration - the new ToolCard tests pass and the suite shows 37 passed with 6 failures in SettingsView.test.tsx. Those 6 failures reproduce on clean origin/main in this environment (localStorage is undefined under the local Node 26 runtime, Cannot read properties of undefined (reading 'getItem')), so they are pre-existing here and not caused by this change. CI runs the same suite green.
• mise run build passed
• bun run test:e2e blocked in this environment. Electron fails to launch with Library not loaded: @rpath/Electron Framework.framework, and all 43 e2e tests skip. Noted once here per the fall-through rule and not retried.

Proof:

• Capture method (b) succeeded through the renderer. A temporary Vite proof page rendered an expanded bash tool card with long output, and a scripted Chrome capture saved .tmp/proof/tool-card-truncated.png and .tmp/proof/tool-card-expanded.png. The capture log recorded has Show more: true, truncated (no END-MARKER): true, has Copy buttons: true, then after clicking Show more, expanded (has END-MARKER): true. The expanded screenshot shows the Input and Output headings, both Copy buttons, the full log text, and the Show less toggle. The PNGs are kept under .tmp/proof/ locally and are not committed, matching the scratch-capture rule for this repo. The temporary proof page was removed before committing.
• Capture method (a) was blocked by the Electron launch failure above, so method (c) carries the logic proof. New integration tests in ToolCard.test.tsx: copies the exact output text and shows Copied and truncates long output and expands on Show more. Both failed before the change (2 failed, 2 passed) and pass after (4 passed).

Known gaps and follow-ups:

• No diff rendering for edit or write input yet. That remains a follow-up slice on Render tool calls as interactive cards #2.
• Parent Render tool calls as interactive cards #2 stays open. This slice covers copy and truncation only.