[Web][W2] Composite Widgets and App-Shell Patterns

Build higher-level composites and reusable application shell layouts.

Acceptance Criteria

• Composite widgets implemented (forms, data panels, nav shells, list/table flows).
• At least one end-to-end app-shell example uses only shared widget APIs.
• Interaction patterns documented and browser-smoke tested.

Tembo-sized implementation issues

• #79 — forms, validation, and action patterns
• #80 — list, table, detail, and data-panel patterns
• #81 — responsive application shell and navigation

All three may run concurrently after #77 and #78 are visually accepted. This parent owns cohesive cross-component review, not implementation commits.

automation:
  eligible: false
  executor_profile: tembo
  readiness: rollup
  primary_repository: TinyChain-Inc/client
  base_branch: main
  writable_scope: []
  prerequisites:
    - "#79"
    - "#80"
    - "#81"
  concurrency_group: ui-composites-rollup
  required_commands: []
  external_actions: none
  draft_pr_only: true
  completion_authority: human
  visual_validation:
    required: true
    baseline_update_requires: human-visual-approval

Start by reading the prerequisite issues #77 and #78, then review the implementation scopes in #79, #80, and #81. The parent is complete when the composite widgets and app-shell example are cohesively reviewed, interaction patterns are documented, browser-smoke testing is done, and required visual validation receives human approval.