feat(agent): add InitMiniApp defaults and simplify assistant config

[wsp1911]

Summary

Add InitMiniApp to the default tool sets for Claw and Cowork, and simplify the assistant configuration UI to match the actual shared defaults model.

Fixes #

Type and Areas

Type:

Feature / UI/UX / refactor

Areas:

Rust core, web UI, i18n

Motivation / Impact

This change does two things:

1. Updates the Rust mode definitions so both Claw and Cowork include InitMiniApp in their default tools, with focused tests covering the new default behavior.
2. Reworks the assistant configuration experience in the web UI so it reflects the real shared Claw default model setup instead of the old template-slot mental model.

User-facing impact:

• Assistant configuration now uses a single shared default-model selector for Claw.
• The selector reuses the chat input model selector behavior, including the corrected downward dropdown placement for the profile scene.
• Misleading context-usage estimate UI has been removed from the assistant configuration/template surfaces.
• Frontend support for IDENTITY.md modelPrimary / modelFast fields has been removed.
• Assistant/profile copy has been updated from “template” wording toward “assistant config” / shared-default wording.

Verification

• pnpm run type-check:web
• pnpm --dir src/web-ui run test:run src/app/scenes/my-agent/identityDocument.test.ts
• pnpm run i18n:audit

Not run:

• Rust checks/tests were not run for the staged claw.rs / cowork.rs changes.

Reviewer Notes

• The staged diff spans both Rust mode defaults and the assistant/profile web UI.
• The web UI changes intentionally remove the old mock token-estimate path (useTokenEstimate.ts) rather than preserving dead estimate logic.
• The profile-scene model selector now supports configurable dropdown placement so the existing chat input behavior remains unchanged while the assistant config page can open downward.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.