pi v0.84.1：新增 Qwen 内置提供商、认证检查与全屏交互改进

New Features

• Qwen Token Plan Individual — Use the built-in provider for models documented for Individual subscriptions. See API Keys.
• Authentication readiness checks — Use pi auth check to verify provider or model credentials, optionally emitting the resolved credential.
• Improved fullscreen interaction — Select words and paragraphs with multiple clicks and configure half-page transcript scrolling. See TUI Fullscreen Viewport.
• Terminating blocked tool calls — Extension tool_call handlers can stop all-terminating batches without another model call. See Tool Events.

Added

• Added Qwen Token Plan Individual as a built-in provider with its documented subscription model catalog and the shared international QWEN_TOKEN_PLAN_API_KEY. See API Keys (#7659 by @arasovic).
• Added pi auth check provider/model auth preflight with optional credential output (#7152).
• Added terminate support to blocked extension tool_call events so all-terminating batches can skip the automatic follow-up model call. See Tool Events (#7715 by @muyiyr).
• Added inherited double-click word and whitespace selection, granularity-aware drag selection, and triple-click paragraph selection in fullscreen mode (#7725, #7733 by @volsa).
• Added inherited unbound half-page transcript scrolling actions for fullscreen mode. See TUI Fullscreen Viewport (#7735).

Changed

• Softened the bash tool's PI_* environment guideline in an attempt to reduce unnecessary inspection commands (#7128).
• Reduced worst-case automatic terminal theme detection delay from 200 ms to 100 ms by probing color-scheme and background support concurrently.

Fixed

• Fixed Bun standalone binaries crashing on startup when the cwd contains a bunfig.toml with preload by compiling with --no-compile-autoload-bunfig (#7685 by @geril07).
• Fixed extension TUI method wrappers recursing indefinitely when delegating to the original method (#7731).
• Fixed right-click not pasting clipboard text in fullscreen mode on Windows.
• Fixed inherited Agent.reset() clearing transcript and runtime state during active runs; it now rejects until the agent is idle (#7717 by @wesleyzhangwq).
• Fixed inherited LaTeX relation, multiplication, and named-operator spacing, and matrix composition with stacked fractions, operator limits, and adjacent matrices.
• Reduced inherited fullscreen mouse event volume under tmux, Zellij, and GNU Screen by using button-motion tracking instead of all-motion tracking.