Add task-handler parse messages and their parse-channel union

[jason810496]

Stack (bottom to top), on native #74037 (stack #74170): #73973, #73974, #73975, #74317, #73976, #74067, #74135, #74140, #74141, #73971, #74030, #74031, #74032, #74136, #74137, #74138, #74139

To check each stub task against the task handler its artifact registers (ADR-0011), the Dag processor has to ask a Lang-SDK runtime which handlers an artifact registers. This PR adds the messages for that (ADR-0012). Nothing sends them yet: #73974 adds the probe.

TaskHandlerParseRequest(  # Dag processor -> runtime
    file="/bundles/go-task-handlers/etl",
    bundle_path=Path("/bundles/go-task-handlers"),
    bundle_name="go-task-handlers",
)

TaskHandlerParsingResult(  # runtime -> Dag processor
    fileloc="/bundles/go-task-handlers/etl",
    task_handlers={  # every handler the artifact registers, keyed by Dag id
        "etl": [
            TaskHandlerDeclaration(
                task_id="extract",
                binding="named",
                params=[TaskHandlerParam(name="day", value_schema={"type": "string"}, exact_name=True)],
            ),
            TaskHandlerDeclaration(
                task_id="load",
                binding="positional",
                params=[TaskHandlerParam(name=None, value_schema={"type": "string"})],
            ),
        ],
    },
)

# A runtime that cannot list a handler's params, such as TypeScript
TaskHandlerDeclaration(task_id="report", binding="named", params=None)

• The request names no Dags. The runtime answers with every handler the artifact registers, and the answer depends only on the artifact, so one probe serves every Dag whose stub tasks resolve to it.
• Each SDK binds stub-task arguments differently, so every declaration carries a required binding:
  • positional: by position (Go flat params, Java TaskArgs). A count or type mismatch fails the Dag file's import.
  • named: by name in any order, ignoring case and _ unless exact_name is set (Go structs, Java TaskInput). A type mismatch fails the import, while an argument or param that matches nothing is only a warning.
• params=None means the runtime cannot list the handler's params (TypeScript, whose types are erased), so only the handler's presence is checked.
• value_schema reuses ArgValueSchema, which stub tasks' arg_bindings already use, so the check compares one type.
• ToManager gains TaskHandlerParsingResult with no shared handler: only the probe class in Probe a Lang-SDK artifact for its task handlers #73974 handles it, and a Dag parse answers it as an unhandled request.
• The supervisor schema version does not move, because a brand-new message needs no VersionChange. The TS SDK types and the Go SDK models are regenerated, and the Java copy is refreshed in Java SDK: answer TaskHandlerParseRequest with registered handlers #74317.
• ADR-0011, ADR-0012 and ADR-0013 describe the messages as built.

---

Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-by: Claude Code (Opus 5.5) following the guidelines