feat: accept object form for toolsConfig values

[Evanfeenstra]

What

toolsConfig values can now optionally be an object, in addition to the existing string | boolean | null forms. This lets a caller pass a description override and tool-specific options at once — e.g. graph_sub_agent's maxDepth/maxSteps (follow-up to #1461).

Fully backwards compatible.

Value	Meaning
true	enable (default description)
false	disable
"some string"	enable + use string as description override
null	keep default
{ ... }	new — enable (unless enabled: false) + carry description and options

{
  "toolsConfig": {
    "graph_sub_agent": { "description": "Explore the graph...", "maxDepth": 3, "maxSteps": 15 },
    "logs_agent": { "description": "custom desc" },
    "bash": { "enabled": false }
  }
}

How

• New types in tools.ts: ToolConfigObject (enabled?, description?, maxDepth?, maxSteps?) and ToolConfigValue = string | boolean | null | ToolConfigObject.
• Two helpers centralize all interpretation of a config value:
  • toolConfigEnabled(v) — truthiness that also honors { enabled: false }.
  • toolConfigDescription(v) — pulls the string override or object.description.
• Routed every existing toolsConfig read through the helpers instead of ad-hoc if (toolsConfig.X) / typeof … === "string" checks: the opt-in tools (ask_clarifying_questions, logs_agent, str_replace_based_edit_tool, apply_patch, generate_*, concepts), the generic filter loop, and the 3 truthiness sites in agent.ts.
• The generic filter loop now also applies object description overrides and honors { enabled: false } for any tool.
• graph_sub_agent reads maxDepth/maxSteps from the object form (previously hardcoded), making recursion depth user-configurable.

Testing

• npx tsc --noEmit clean
• tools + docgen suites — 56/56 pass