refactor: delete the unreachable get_problem_flows tool wrapper

[chubes4]

Goal

Delete the unreachable GetProblemFlows model-tool wrapper without adding, removing, or changing any public capability.

Parent: #3332

Current state

DataMachine\Api\Chat\Tools\GetProblemFlows exists at inc/Api/Chat/Tools/GetProblemFlows.php and wraps the canonical datamachine/get-problem-flows ability owned by DataMachine\Abilities\Job\ProblemFlowsAbility.

Current ToolServiceProvider neither imports nor instantiates the wrapper, and no built-in ability projection registers get_problem_flows. The model-facing tool is absent from the current runtime while its unused class remains in production source.

Scope

Delete inc/Api/Chat/Tools/GetProblemFlows.php.

Do not change:

• inc/Engine/AI/Tools/ToolServiceProvider.php
• inc/Engine/AI/Tools/ability-tool-projections.php
• inc/Abilities/Job/ProblemFlowsAbility.php

Add or update focused tests proving the current lifecycle and canonical ability surface remain unchanged.

Required behavior preservation

• get_problem_flows remains absent from model-tool resolution in pipeline_editor, chat, and pipeline modes.
• datamachine/get-problem-flows remains registered and executable.
• Preserve the ability slug, schemas, threshold default, permission callback, REST visibility, and result behavior.
• Preserve ToolServiceProvider registration order and filter timing exactly.
• Do not add a projection declaration, replacement class, compatibility alias, callback, generic wrapper, or projection feature.
• Do not modify REST or CLI contracts.

Why deletion, not projection

Projecting the ability would add a model-facing capability that is absent on current main. The dormant wrapper also had a flattened presentation shape that the current declarative projection mechanism does not express. Do not extend the projection mechanism for dead code.

Production LOC target

Expected net deletion: approximately 100-110 production PHP lines. Record exact totals in the PR.

Tests

Update tests/Unit/AI/Tools/ChatToolsAvailabilityTest.php to prove get_problem_flows remains absent from relevant model-tool modes. Add focused inventory coverage only if executable lifecycle coverage cannot prove the boundary.

Run focused chat-tool availability and problem-flow ability tests, existing projection/ability adapter smokes, complete Homeboy tests, package build, changed-file quality gates, and git diff --check.

Collision constraint

Open PR #3361 does not touch this wrapper or focused availability test. Do not modify its package-audit evidence or packaging files.

Constraints

• No public contract or capability changes.
• No new framework code.
• No version bump or changelog edit.
• Conventional refactor: commit.
• PR only; do not release or deploy.

Refs #3332
Parent: #3113