feat: workflow microflow actions and COMPLETE_TASK page action

[engalar]

Summary

• Add full MDL support (read/write) for all 11 workflow microflow action types that were previously falling through to -- Unknown action in DESCRIBE
• Add COMPLETE_TASK 'OutcomeName' as a new ACTIONBUTTON action type for workflow task pages
• Closes feat: MDL support for workflow microflow actions (GetWorkflowDataAction, WorkflowCallAction, etc.) #156, closes Feature request: CALL WORKFLOW statement in microflows #136, closes Feature: support COMPLETE_TASK action type for ACTIONBUTTON in page/snippet MDL #155

Workflow Microflow Actions

Action	MDL Syntax
GetWorkflowDataAction	$Data = GET WORKFLOW DATA $Wf AS Module.Workflow
WorkflowCallAction	$Wf = CALL WORKFLOW Module.WF ($Context)
GetWorkflowsAction	$Wfs = GET WORKFLOWS FOR $Obj
GetWorkflowActivityRecordsAction	$Records = GET WORKFLOW ACTIVITY RECORDS $Wf
WorkflowOperationAction	WORKFLOW OPERATION ABORT/PAUSE/CONTINUE/RESTART/RETRY/UNPAUSE $Wf
SetTaskOutcomeAction	SET TASK OUTCOME $Task 'OutcomeName'
OpenUserTaskAction	OPEN USER TASK $Task
NotifyWorkflowAction	NOTIFY WORKFLOW $Wf
OpenWorkflowAction	OPEN WORKFLOW $Wf
LockWorkflowAction	LOCK WORKFLOW $Wf / LOCK WORKFLOW ALL
UnlockWorkflowAction	UNLOCK WORKFLOW $Wf / UNLOCK WORKFLOW ALL

COMPLETE_TASK Page Action

ACTIONBUTTON btnApprove (
  Caption: 'Approve',
  Action: COMPLETE_TASK 'Approve',
  ButtonStyle: Success
)

Implementation

Full pipeline for each action type:

• SDK types (sdk/microflows/microflows_actions.go)
• BSON parser (sdk/mpr/parser_microflow_workflow.go)
• BSON writer (sdk/mpr/writer_microflow_workflow.go)
• MDL formatter for DESCRIBE (cmd_microflows_format_action.go)
• ANTLR4 grammar rules (MDLLexer.g4, MDLParser.g4)
• AST nodes (mdl/ast/ast_microflow_workflow.go)
• Visitor (mdl/visitor/visitor_microflow_workflow.go)
• Executor/builder (cmd_microflows_builder_workflow.go)

Test plan

• make build passes
• make test — all existing tests pass (no regression)
• mxcli check workflow-microflow-actions.mdl — syntax OK
• mxcli check complete-task-action.mdl — syntax OK
• Existing page test (03-page-examples.mdl) still passes with new DATA token
• Test with real MPR containing workflow microflows to verify DESCRIBE output
• Test CREATE with mxcli exec against a real project and open in Studio Pro

[ako]

Review

Well-structured full-stack implementation — 11 workflow action types + COMPLETE_TASK, each wired through all 8 pipeline layers. ~1,500 lines of real code.

What's good

• Complete pipeline for every action: SDK types, parser, writer, formatter, grammar, AST, visitor, executor
• Grammar design is clean — natural English consistent with existing MDL patterns
• Polymorphic dispatch for WorkflowOperationAction correctly handles 6 operation types
• DESCRIBE formatter output matches grammar syntax (re-parseable)
• MDL examples cover all actions

Concerns

DATA and OPEN tokens could conflict with identifiers. These are common words that could appear as entity/attribute names in real projects. CREATE ENTITY Mod.Data (...) or an attribute named Data would break. Can DATA be restricted to the getWorkflowDataStatement context only, or made a soft keyword?

No unit tests for the new code. The test plan only lists mxcli check (syntax parsing) and no-regression. There are no unit tests for the 11 new parser functions, writer functions, or formatter functions. A roundtrip test for at least one action type would add confidence, especially since the BSON field names haven't been verified against a live MPR yet (per test plan).

Minor

• COMPLETE_TASK as a single underscore-joined lexer token is unusual but avoids ambiguity. Acceptable.