refactor: move package to internal/clipx

[karngyan]

clipx is a CLI tool, not a library — nobody should be importing github.com/gomantics/clipx/clipx.

Moves the package to internal/clipx/ which:

• Eliminates the redundant clipx/clipx import path
• Signals clearly that these are internal implementation details
• Follows the standard Go convention for CLI projects

before:  github.com/gomantics/clipx/clipx     (redundant, importable)
after:   github.com/gomantics/clipx/internal/clipx  (internal, Go enforces non-importability)

All tests pass.

[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%