docs(poster): update docs

[adcondev]

This pull request removes several documentation files related to package design, nitpicks, raw command usage, and release processes. The main impact is the cleanup of internal documentation that may no longer be relevant or is being consolidated elsewhere.

The most important changes are:

Documentation Cleanup:

• Removed docs/CONN_NITPICKS.md, which detailed architecture issues, implementation gaps, and refactoring suggestions for the connection package.
• Removed docs/PROFILE_NITPICKS.md, which contained observations and improvement suggestions for the pkg/profile package.
• Removed docs/RAW_COMMAND.md, which documented raw command limitations, usage, and safety considerations.
• Removed docs/RELEASING.md, which described the CI/CD pipeline and release process for the project.
• Removed docs/TEMPLATE.md, which provided Go package and godoc templates for ESC/POS command implementations.

[github-actions]

👋 Thanks for opening this PR, @adcondev!

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[github-actions]

⚡ Benchmark Results

📈 Performance Comparison

📊 Click to expand detailed results

Current Branch Results

BenchmarkNewDocument-4    	1000000000	         0.3523 ns/op	       0 B/op	       0 allocs/op
BenchmarkBuildSimple-4    	 4071690	       298.7 ns/op	     240 B/op	       4 allocs/op
BenchmarkBuildComplex-4   	  420312	      2557 ns/op	    1809 B/op	      25 allocs/op
BenchmarkToJSON-4         	  572457	      1861 ns/op	     592 B/op	       3 allocs/op
BenchmarkParseDocument_Minimal-4    	  580780	      2010 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Receipt-4    	  109023	     11042 ns/op	    2392 B/op	      34 allocs/op
BenchmarkCommandUnmarshal_Text-4    	  476454	      2349 ns/op	     568 B/op	      19 allocs/op
BenchmarkCommandUnmarshal_Table-4   	  318790	      3557 ns/op	     944 B/op	      21 allocs/op
BenchmarkTextCommandParsing-4       	  593637	      1807 ns/op	     544 B/op	      16 allocs/op
BenchmarkTableCommandParsing-4      	  278985	      4099 ns/op	    1000 B/op	      29 allocs/op
BenchmarkParseHexString-4           	 7337930	       162.4 ns/op	      48 B/op	       2 allocs/op
BenchmarkCleanHexString-4           	 5927205	       202.3 ns/op	      64 B/op	       2 allocs/op
BenchmarkContainsSequence-4         	260647726	         4.576 ns/op	       0 B/op	       0 allocs/op
BenchmarkCheckCriticalCommands-4    	30783314	        39.06 ns/op	       0 B/op	       0 allocs/op
BenchmarkDocument_Validate-4       	14742733	        82.03 ns/op	       0 B/op	       0 allocs/op
BenchmarkParseDocument_Simple-4    	  557228	      2189 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Complex-4   	  153259	      7709 ns/op	    1352 B/op	      26 allocs/op
BenchmarkPrintImage_Small-4             	     639	   1915532 ns/op	 3469935 B/op	      24 allocs/op
BenchmarkPrintImage_Medium-4            	     316	   3759161 ns/op	 5481086 B/op	      24 allocs/op
BenchmarkPrintImage_ThermalPreview-4    	     130	   9094295 ns/op	 5231174 B/op	  230423 allocs/op

Base Branch Results

BenchmarkNewDocument-4    	1000000000	         0.3524 ns/op	       0 B/op	       0 allocs/op
BenchmarkBuildSimple-4    	 4079752	       300.6 ns/op	     240 B/op	       4 allocs/op
BenchmarkBuildComplex-4   	  435140	      2586 ns/op	    1809 B/op	      25 allocs/op
BenchmarkToJSON-4         	  570084	      1878 ns/op	     592 B/op	       3 allocs/op
BenchmarkParseDocument_Minimal-4    	  583893	      2002 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Receipt-4    	  106898	     11239 ns/op	    2392 B/op	      34 allocs/op
BenchmarkCommandUnmarshal_Text-4    	  476191	      2335 ns/op	     568 B/op	      19 allocs/op
BenchmarkCommandUnmarshal_Table-4   	  315771	      3571 ns/op	     944 B/op	      21 allocs/op
BenchmarkTextCommandParsing-4       	  596042	      1825 ns/op	     544 B/op	      16 allocs/op
BenchmarkTableCommandParsing-4      	  283280	      4085 ns/op	    1000 B/op	      29 allocs/op
BenchmarkParseHexString-4           	 7339334	       161.1 ns/op	      48 B/op	       2 allocs/op
BenchmarkCleanHexString-4           	 5805243	       206.5 ns/op	      64 B/op	       2 allocs/op
BenchmarkContainsSequence-4         	262235704	         4.587 ns/op	       0 B/op	       0 allocs/op
BenchmarkCheckCriticalCommands-4    	30932605	        39.12 ns/op	       0 B/op	       0 allocs/op
BenchmarkDocument_Validate-4       	14772691	        82.97 ns/op	       0 B/op	       0 allocs/op
BenchmarkParseDocument_Simple-4    	  551392	      2150 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Complex-4   	  150636	      7682 ns/op	    1352 B/op	      26 allocs/op
BenchmarkPrintImage_Small-4             	     576	   1887245 ns/op	 3469934 B/op	      24 allocs/op
BenchmarkPrintImage_Medium-4            	     298	   3789236 ns/op	 5481087 B/op	      24 allocs/op
BenchmarkPrintImage_ThermalPreview-4    	     132	   9153904 ns/op	 5231186 B/op	  230423 allocs/op

💡 Note: Use benchstat for statistical comparison

🎯 Summary

• Total Benchmarks: 32
• Average Speed: 2598969 ns/op
• Average Memory: 2396763 B/op
• Average Allocations: 41077 allocs/op