🧪 Add unit tests for TabEngine.Render

[adcondev]

Implemented unit tests for pkg/tables/table_engine.go covering Render method. Verified happy paths, edge cases, and error conditions. Also updated LEARNING.md with testing strategy.

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PR created automatically by Jules for task 16145180427249992677 started by @adcondev

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[github-actions]

👋 Thanks for opening this PR, @adcondev!

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• ✅ All tests pass
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[github-actions]

⚡ Benchmark Results

📈 Performance Comparison

📊 Click to expand detailed results

Current Branch Results

BenchmarkNewDocument-4    	1000000000	         0.3131 ns/op	       0 B/op	       0 allocs/op
BenchmarkBuildSimple-4    	 3697239	       324.3 ns/op	     240 B/op	       4 allocs/op
BenchmarkBuildComplex-4   	  424239	      2737 ns/op	    1809 B/op	      25 allocs/op
BenchmarkToJSON-4         	  539599	      2070 ns/op	     592 B/op	       3 allocs/op
BenchmarkParseDocument_Minimal-4    	  490782	      2316 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Receipt-4    	   94402	     12607 ns/op	    2392 B/op	      34 allocs/op
BenchmarkCommandUnmarshal_Text-4    	  401947	      2693 ns/op	     568 B/op	      19 allocs/op
BenchmarkCommandUnmarshal_Table-4   	  275282	      4193 ns/op	     944 B/op	      21 allocs/op
BenchmarkTextCommandParsing-4       	  524598	      2124 ns/op	     544 B/op	      16 allocs/op
BenchmarkTableCommandParsing-4      	  240356	      4864 ns/op	    1000 B/op	      29 allocs/op
BenchmarkParseHexString-4           	 8651936	       135.8 ns/op	      48 B/op	       2 allocs/op
BenchmarkCleanHexString-4           	 6647467	       179.4 ns/op	      64 B/op	       2 allocs/op
BenchmarkContainsSequence-4         	366006026	         3.252 ns/op	       0 B/op	       0 allocs/op
BenchmarkCheckCriticalCommands-4    	31990150	        37.72 ns/op	       0 B/op	       0 allocs/op
BenchmarkDocument_Validate-4       	14539770	        82.71 ns/op	       0 B/op	       0 allocs/op
BenchmarkParseDocument_Simple-4    	  478741	      2423 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Complex-4   	  135884	      8671 ns/op	    1352 B/op	      26 allocs/op
BenchmarkPrintImage_Small-4             	     603	   2002406 ns/op	 3469947 B/op	      24 allocs/op
BenchmarkPrintImage_Medium-4            	     315	   3755101 ns/op	 5481087 B/op	      24 allocs/op
BenchmarkPrintImage_ThermalPreview-4    	     139	   8668213 ns/op	 5235277 B/op	  230723 allocs/op

Base Branch Results

BenchmarkNewDocument-4    	1000000000	         0.3171 ns/op	       0 B/op	       0 allocs/op
BenchmarkBuildSimple-4    	 3550774	       322.9 ns/op	     240 B/op	       4 allocs/op
BenchmarkBuildComplex-4   	  401906	      2812 ns/op	    1809 B/op	      25 allocs/op
BenchmarkToJSON-4         	  545776	      2072 ns/op	     592 B/op	       3 allocs/op
BenchmarkParseDocument_Minimal-4    	  514668	      2311 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Receipt-4    	   93900	     12621 ns/op	    2392 B/op	      34 allocs/op
BenchmarkCommandUnmarshal_Text-4    	  419192	      2692 ns/op	     568 B/op	      19 allocs/op
BenchmarkCommandUnmarshal_Table-4   	  277488	      4169 ns/op	     944 B/op	      21 allocs/op
BenchmarkTextCommandParsing-4       	  527095	      2104 ns/op	     544 B/op	      16 allocs/op
BenchmarkTableCommandParsing-4      	  242984	      4770 ns/op	    1000 B/op	      29 allocs/op
BenchmarkParseHexString-4           	 7584562	       155.8 ns/op	      48 B/op	       2 allocs/op
BenchmarkCleanHexString-4           	 6192847	       189.6 ns/op	      64 B/op	       2 allocs/op
BenchmarkContainsSequence-4         	296019583	         4.064 ns/op	       0 B/op	       0 allocs/op
BenchmarkCheckCriticalCommands-4    	32902302	        37.20 ns/op	       0 B/op	       0 allocs/op
BenchmarkDocument_Validate-4       	14505379	        82.87 ns/op	       0 B/op	       0 allocs/op
BenchmarkParseDocument_Simple-4    	  491582	      2415 ns/op	     568 B/op	      14 allocs/op
BenchmarkParseDocument_Complex-4   	  137683	      8550 ns/op	    1352 B/op	      26 allocs/op
BenchmarkPrintImage_Small-4             	     579	   2013758 ns/op	 3469949 B/op	      24 allocs/op
BenchmarkPrintImage_Medium-4            	     327	   3797112 ns/op	 5481085 B/op	      24 allocs/op
BenchmarkPrintImage_ThermalPreview-4    	     139	   8589038 ns/op	 5231184 B/op	  230423 allocs/op

💡 Note: Use benchstat for statistical comparison

🎯 Summary

• Total Benchmarks: 32
• Average Speed: 2683008 ns/op
• Average Memory: 2396936 B/op
• Average Allocations: 41093 allocs/op