Refactor widget serialization format + Unify decomp result type + Support lazy IML reader for resolving dependencies

[hon-gyu]

imandrax-api-models:

• add TasksRepr for task widget serialization; unify task repr
• FIX(client): get artifact incorrectly enter and close async context
• unified DecomposeRes type: avoid serialization issue with MIR regions; carry one parsed region data
  • Follow-up: this new type should replace DecomposeRes and EnrichedDecomposeRes; region / group related stats types need a cleanup as well

imandrax-tools:

• switch to unified task repr for tasks widget
• REFA(widget): split modules
• FEAT(widget): HTML embed utils
• Follow-up: find a principled way to show api response (especially for error case, but not limited to error case) in widget

iml-query:

• Support lazy IML reader for resolving dependencies