feat: Add advanced agent configuration features to TrueFoundry UI

[harshil-2096]

Summary

Closes #

Changes

How was this tested?

Checklist

• I have read the contributing guidelines
• pnpm build, pnpm test, pnpm typecheck, pnpm lint:ci, and pnpm format:check pass locally
• Tests added/updated where it makes sense
• No hand-edits to generated code (packages/trueforge-sdk, .github/fern/openapi/openapi.json, docs/openapi.json) — fork PRs omit SDK regen; maintainers regenerate after merge
• Docs / .env.example updated if configuration or behavior changed

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Note

Medium Risk
Touches agent spec persistence, MCP tool allowlists, and runtime/sandbox defaults across live draft and save flows; regressions could change agent behavior without an explicit save.

Overview
Adds a live Agent Config side drawer for mutable composer modes, opened from a new composer control. Draft changes (instructions with debounced sync, model, runtime, MCP servers with per-tool selection, and skills) apply to the active session immediately; Save Agent now uses a cloned working copy and the same shared editor stack, so canceling the dialog does not revert the live draft.

The compact Tools picker is limited to connectors and skills—capabilities and broader runtime settings moved into Runtime Config modals and summaries. Model pickers can show optional context / max output metadata from the catalog; the harness builder wires getMcpTools for lazy MCP tool lists. Sandbox is no longer auto-enabled when the capability is merely available; adding a skill still turns sandbox on when supported.

Layouts (sidebar, drawer, stack) host the drawer; shell state adds agentConfigOpen with mutual exclusion against settings/library/sessions. Bumps @truefoundry/assistant-ui-runtime to 0.1.26 (minor package changeset).

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🦋 Changeset detected

Latest commit: 881dd79

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@truefoundry/trueforge-ui	Minor

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