docs: simplify README

[karngyan]

Cuts the README from ~165 lines to ~74. Removes noise, keeps signal.

Removed:

• "Ports" section (port already in diagram + design)
• Verbose defaults write commands for disabling Universal Clipboard (kept the System Settings one-liner as a tip)
• Separate "From source" install subsection (lives in CONTRIBUTING.md)
• "Reliability", "Limits", "Loop prevention" as separate subsections

Condensed:

• Install methods into one flat section
• Quick start into a tighter 2-step flow
• Design into bullet points + wire format table
• Troubleshooting into single-line entries
• Config JSON on one line

Kept everything a user needs: install, pair, commands, add more macs, config, how it works, troubleshooting.

[github-actions]

📊 Code Coverage Report

total:								(statements)		26.8%

Coverage by file

github.com/gomantics/clipx/cmd/clipx/main.go:21:		getVersion		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:31:		main			0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:75:		printUsage		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:100:		cmdRun			0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:133:		cmdPair			0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:162:		cmdUnpair		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:198:		cmdPeers		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:213:		cmdStatus		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:240:		cmdUpdate		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:297:		launchAgentPath		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:302:		logFilePath		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:307:		cmdInstall		0.0%
github.com/gomantics/clipx/cmd/clipx/main.go:358:		cmdUninstall		0.0%
github.com/gomantics/clipx/internal/clipx/clipboard.go:49:	Read			0.0%
github.com/gomantics/clipx/internal/clipx/clipboard.go:55:	Write			0.0%
github.com/gomantics/clipx/internal/clipx/config.go:16:		ConfigPath		100.0%
github.com/gomantics/clipx/internal/clipx/config.go:22:		LoadConfig		77.8%
github.com/gomantics/clipx/internal/clipx/config.go:38:		SaveConfig		71.4%
github.com/gomantics/clipx/internal/clipx/net.go:15:		ResolveAddr		88.9%
github.com/gomantics/clipx/internal/clipx/net.go:35:		PingPeer		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:50:		NewNode			0.0%
github.com/gomantics/clipx/internal/clipx/node.go:55:		NewNodeWithClipboard	0.0%
github.com/gomantics/clipx/internal/clipx/node.go:88:		Start			0.0%
github.com/gomantics/clipx/internal/clipx/node.go:97:		Stop			0.0%
github.com/gomantics/clipx/internal/clipx/node.go:106:		connectPeer		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:117:		sendToPeer		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:145:		listen			83.3%
github.com/gomantics/clipx/internal/clipx/node.go:195:		handleClip		75.0%
github.com/gomantics/clipx/internal/clipx/node.go:203:		handleChunk		81.5%
github.com/gomantics/clipx/internal/clipx/node.go:254:		applyClipboard		85.7%
github.com/gomantics/clipx/internal/clipx/node.go:278:		watchClipboard		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:323:		sendToAllPeers		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:374:		maintenance		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:407:		clipPreview		100.0%
github.com/gomantics/clipx/internal/clipx/node.go:416:		isTimeout		0.0%
github.com/gomantics/clipx/internal/clipx/node.go:423:		isConnectionError	0.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:47:	encodeMessage		100.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:58:	decodeMessage		100.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:72:	encodeClipPayload	100.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:81:	decodeClipPayload	100.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:89:	encodeChunkPayload	100.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:99:	decodeChunkPayload	100.0%
github.com/gomantics/clipx/internal/clipx/protocol.go:111:	HashContent		100.0%
total:								(statements)		26.8%