docs: 加上应用图标和社交预览图

- docs/icon.png       满幅方图，去掉 icns 里四周 100px 的透明留白 ——
                      GitHub 会自己加圆角，留白会让图标缩成小小一颗
- docs/social-preview.png  1280×640。仓库被分享到 Twitter / Slack / 飞书时
                      唯一会被看到的东西；没有它链接展开是一片灰底加一行小字
- README 头部放上图标

社交预览图由 Resources/make-social.swift 生成，图标直接读 AppIcon.icns
而不是重画一遍 —— 两处各画一遍必然漂移，"两个地方的图标不一样"
是最廉价也最刺眼的破绽。

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -1,6 +1,10 @@
-# Vibe Foreman Free
+<p align="center">
+  <img src="docs/icon.png" width="128" alt="Vibe Foreman">
+</p>
 
-把 MacBook 的刘海变成本地 AI 编程 agent 的**工头**。
+<h1 align="center">Vibe Foreman Free</h1>
+
+<p align="center">把 MacBook 的刘海变成本地 AI 编程 agent 的<b>工头</b>。</p>
 
 它不只是让你看见 agent 在干嘛 —— 它盯着它们**有没有真的把活干完**。
 

Resources/make-social.swift

@@ -0,0 +1,142 @@
+import AppKit
+import CoreGraphics
+import Foundation
+import ImageIO
+
+// GitHub 的社交预览图（1280×640）。
+//
+// 这张图是仓库被分享到 Twitter / Slack / 飞书时唯一会被看到的东西 ——
+// 没有它，链接展开后是一片灰底加一行小字，看起来像个废弃项目。
+//
+// 沿用 app 图标的视觉语言：近黑底 + 青→蓝→紫→品红→橙的渐变胶囊。
+// 图标本身直接读 AppIcon.icns 里那张 1024，不重画一遍 ——
+// 两处各画一遍必然漂移，而"两个地方的图标不一样"是最廉价也最刺眼的破绽。
+
+let W: CGFloat = 1280
+let H: CGFloat = 640
+
+let here = URL(fileURLWithPath: #filePath).deletingLastPathComponent()
+let iconURL = here.appendingPathComponent("AppIcon.icns")
+let outURL = here.deletingLastPathComponent()
+    .appendingPathComponent("docs/social-preview.png")
+
+guard let iconImage = NSImage(contentsOf: iconURL) else {
+    FileHandle.standardError.write(Data("找不到 AppIcon.icns\n".utf8))
+    exit(1)
+}
+
+guard let ctx = CGContext(
+    data: nil, width: Int(W), height: Int(H),
+    bitsPerComponent: 8, bytesPerRow: 0,
+    space: CGColorSpaceCreateDeviceRGB(),
+    bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+) else { exit(1) }
+
+ctx.setAllowsAntialiasing(true)
+
+// ── 底：近黑，带一点从左下往右上的提亮，别做成死板的纯色块。
+let space = CGColorSpaceCreateDeviceRGB()
+if let bg = CGGradient(
+    colorsSpace: space,
+    colors: [
+        CGColor(red: 0.055, green: 0.055, blue: 0.075, alpha: 1),
+        CGColor(red: 0.098, green: 0.094, blue: 0.129, alpha: 1),
+    ] as CFArray,
+    locations: [0, 1]
+) {
+    ctx.drawLinearGradient(
+        bg, start: CGPoint(x: 0, y: 0), end: CGPoint(x: W, y: H), options: []
+    )
+}
+
+// ── 图标背后的光晕。图标是深色的，直接压在深色底上会糊成一团。
+ctx.saveGState()
+let glowCenter = CGPoint(x: 300, y: H / 2)
+if let glow = CGGradient(
+    colorsSpace: space,
+    colors: [
+        CGColor(red: 0.45, green: 0.35, blue: 0.95, alpha: 0.32),
+        CGColor(red: 0.45, green: 0.35, blue: 0.95, alpha: 0),
+    ] as CFArray,
+    locations: [0, 1]
+) {
+    ctx.drawRadialGradient(
+        glow, startCenter: glowCenter, startRadius: 0,
+        endCenter: glowCenter, endRadius: 300, options: []
+    )
+}
+ctx.restoreGState()
+
+// ── 图标
+let iconSide: CGFloat = 300
+let iconRect = CGRect(
+    x: glowCenter.x - iconSide / 2, y: H / 2 - iconSide / 2,
+    width: iconSide, height: iconSide
+)
+var proposed = iconRect
+if let cg = iconImage.cgImage(forProposedRect: &proposed, context: nil, hints: nil) {
+    ctx.draw(cg, in: iconRect)
+}
+
+// ── 文字。用 AppKit 画，CoreText 手搓一遍不值得。
+let gfx = NSGraphicsContext(cgContext: ctx, flipped: false)
+NSGraphicsContext.saveGraphicsState()
+NSGraphicsContext.current = gfx
+
+func draw(_ text: String, at point: CGPoint, size: CGFloat, weight: NSFont.Weight,
+          color: NSColor, tracking: CGFloat = 0) {
+    let style = NSMutableParagraphStyle()
+    style.lineHeightMultiple = 1.1
+    let attrs: [NSAttributedString.Key: Any] = [
+        .font: NSFont.systemFont(ofSize: size, weight: weight),
+        .foregroundColor: color,
+        .kern: tracking,
+        .paragraphStyle: style,
+    ]
+    NSAttributedString(string: text, attributes: attrs).draw(at: point)
+}
+
+let textX: CGFloat = 520
+
+draw("Vibe Foreman", at: CGPoint(x: textX, y: 372), size: 76, weight: .bold,
+     color: .white, tracking: -1.5)
+
+draw("给 vibe coding 当工头", at: CGPoint(x: textX, y: 312), size: 30, weight: .medium,
+     color: NSColor(calibratedRed: 0.72, green: 0.70, blue: 0.85, alpha: 1))
+
+// 这两行是全图唯一在说"它和别的监控工具有什么不同"的地方。
+draw("不只看见 AI agent 在干嘛，", at: CGPoint(x: textX, y: 244), size: 26,
+     weight: .regular, color: NSColor(white: 0.62, alpha: 1))
+draw("还盯着它有没有真的把活干完。", at: CGPoint(x: textX, y: 206), size: 26,
+     weight: .regular, color: NSColor(white: 0.62, alpha: 1))
+
+NSGraphicsContext.restoreGraphicsState()
+
+// ── 底部那道渐变细线：把图标上的配色再点一次，收住整张图。
+if let line = CGGradient(
+    colorsSpace: space,
+    colors: [
+        CGColor(red: 0.30, green: 0.78, blue: 0.95, alpha: 1),
+        CGColor(red: 0.45, green: 0.45, blue: 0.95, alpha: 1),
+        CGColor(red: 0.85, green: 0.35, blue: 0.75, alpha: 1),
+        CGColor(red: 0.98, green: 0.55, blue: 0.35, alpha: 1),
+    ] as CFArray,
+    locations: [0, 0.35, 0.7, 1]
+) {
+    ctx.saveGState()
+    ctx.clip(to: CGRect(x: 0, y: 0, width: W, height: 8))
+    ctx.drawLinearGradient(
+        line, start: CGPoint(x: 0, y: 0), end: CGPoint(x: W, y: 0), options: []
+    )
+    ctx.restoreGState()
+}
+
+guard let image = ctx.makeImage(),
+      let dest = CGImageDestinationCreateWithURL(
+        outURL as CFURL, "public.png" as CFString, 1, nil
+      )
+else { exit(1) }
+
+CGImageDestinationAddImage(dest, image, nil)
+guard CGImageDestinationFinalize(dest) else { exit(1) }
+print("已生成 \(outURL.path)")