Implement A2UI v0.9 basic catalog sample improvements and additions

[jacobsimionato]

The current 29 basic catalog samples (specification/v0_9/json/catalogs/basic/examples/*.json) are primarily static and do not exercise the more dynamic features of the v0.9 specification. This task involves updating these files to natively include features like dynamic templating, client-side functions, and advanced components, as well as creating 4 new advanced samples as described in the project's samples plan.

Key refactors (Retrofitting existing samples):

• Dynamic Templating: Refactor lists in 03, 04, 12, 13, 18, and 21 to use ChildList templates.
• Functions: Integrate formatCurrency, formatDate, formatNumber, and pluralize where appropriate.
• Validation: Add checks and logic to the login form in 09.
• Components: Introduce AudioPlayer (26), Video/Modal (29), Tabs (24), ChoicePicker (19), and CheckBox/DateTimeInput (07).

New Advanced Samples:
Create four new high-fidelity samples:

1. Live Invitation Builder: Reactive two-way data binding.
2. Incremental Dashboard: Progressive structural updates (nodes being swapped/appended).
3. Advanced Form Validator: Deeply nested functions and complex logical validation.
4. Financial Data Grid: Complex layout weighting and alignment across deep hierarchies.

[jacobsimionato]

Coding agent prompt:
You are tasked with retrofitting the existing A2UI v0.9 basic catalog samples and creating 4 new advanced samples to exercise complex protocol behaviors.

Context:

• Protocol Specification: @specification/v0_9/docs/a2ui_protocol.md
• JSON Schemas: @specification/v0_9/json/
• Component Catalog: @specification/v0_9/json/basic_catalog.json
• Implementation Plan: @samples_plan.md
• Target Files: @specification/v0_9/json/catalogs/basic/examples/

Requirements - Retrofitting Existing Samples:

1. Refactor Hardcoded Lists: Convert static child lists in 03, 04, 12, 13, 18, and 21 to use the ChildList object template (mapping over an array in the data model).
2. Apply Formatting Functions: Replace static strings with raw data in the data model and use functions like formatCurrency, formatDate, formatNumber, and pluralize in the component definitions (refer to section 2.2 of @samples_plan.md for specific file mapping).
3. Implement Validation: Add checks to the input fields in 09_login-form.json and a logical and condition to the "Sign In" button.
4. Integrate Missing Components: Update existing samples to include AudioPlayer, Video, Modal, Tabs, ChoicePicker, CheckBox, and DateTimeInput as outlined in section 2.4 of @samples_plan.md.

Requirements - New Advanced Samples:
Create the following files in specification/v0_9/json/catalogs/basic/examples/:

1. 30_live-invitation-builder.json: Implement a side-by-side editor and preview that demonstrates reactive two-way binding.
2. 31_incremental-dashboard.json: A message sequence demonstrating a skeleton UI where loading placeholders are incrementally replaced by structural updates (updateComponents node swaps).
3. 32_advanced-form-validator.json: A form using deeply nested formatString calls and complex checks logic (e.g., or(and(...), and(...))).
4. 33_financial-data-grid.json: A grid demonstrating perfect column alignment using weight properties within Row components inside a List template.

Validation:

• Every modified or new file MUST validate against @specification/v0_9/json/sample.json.
• Ensure all component IDs remain unique within their respective surfaces.
• Verify that data model paths in components correctly resolve to the structures provided in the updateDataModel messages.
• Each sample should contain a logical sequence of createSurface, updateComponents, and updateDataModel messages.