refactor(workflow): Replace hardcoded IconURL with IconURI to enable …

[lvxinyu-1117]

…dynamic icon URL generation, resolving access issues in LAN deployments.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 26.53061% with 36 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/application/workflow/workflow.go	23.80%	32 Missing ⚠️
backend/application/workflow/init.go	0.00%	4 Missing ⚠️

Files with missing lines	Coverage Δ
backend/domain/workflow/entity/node_meta.go	69.23% <ø> (ø)
backend/domain/workflow/internal/nodes/llm/llm.go	59.74% <100.00%> (ø)
...main/workflow/internal/nodes/qa/question_answer.go	68.98% <100.00%> (ø)
...workflow/internal/nodes/receiver/input_receiver.go	65.44% <100.00%> (ø)
backend/application/workflow/init.go	0.00% <0.00%> (ø)
backend/application/workflow/workflow.go	51.26% <23.80%> (-0.42%)	⬇️

... and 3 files with indirect coverage changes

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