[Web][W3.3] Implement State editing, mutation, and conflict/error widgets

[code-tc]

Objective

Add authorized edit/update flows over the canonical JS client with explicit validation, optimistic-state, retry and conflict semantics.

Scope

Scalar and structured edit adapters, mutation progress, typed authorization/validation/conflict failures, confirmation for destructive operations, rollback of optimistic presentation, and refresh after success. Server authorization remains authoritative.

Acceptance criteria

• Mutations use version/idempotency information supported by the client contract.
• Double-submit, retry, offline/reconnect and stale-version cases are deterministic.
• Denials and redacted fields cannot be bypassed by manually invoking widget handlers.
• Focus and unsaved input are preserved across recoverable failures.
• Browser, accessibility, adversarial and screenshot evidence pass human review.

Parent: #9

Required visual evidence

The draft PR must provide a runnable component-gallery route plus before/after screenshots at 390×844, 768×1024, and 1440×900. Cover light, dark, high-contrast, default, hover, focus-visible, disabled, loading, empty, error, and overflow states applicable to the component. Playwright must exercise keyboard interaction and capture deterministic screenshots. A reviewer other than the implementing agent must approve intentional baseline changes; screenshot generation or a passing pixel threshold is not visual approval.

Tembo execution contract

automation:
  eligible: true
  executor_profile: tembo
  readiness: blocked
  primary_repository: TinyChain-Inc/client
  base_branch: main
  writable_scope:
    - web/src/state-widgets/edit/**
    - web/src/ui/gallery/**
    - web/tests/**
    - js/src/**
  prerequisites:
    - "#79"
    - "#82"
    - "TinyChain-Inc/tcv2#53"
  concurrency_group: ui-state-editing
  required_commands:
    - "cd web && npm ci"
    - "cd web && npm run test:all"
  external_actions: none
  draft_pr_only: true
  completion_authority: human
  visual_validation:
    required: true
    browsers: [chromium]
    viewports: [mobile, tablet, desktop]
    evidence: [component-gallery-url, screenshot-bundle, playwright-report]
    baseline_update_requires: human-visual-approval
    failure_policy: never-auto-accept-diff
  budget:
    size: large
    max_revisions: 3
    max_wall_minutes: 120