Adds a Blazor WebAssembly (.NET 10) + Motoko Hello World template.

[mitnick2012]

Overview
The icp-cli templates library has no support for .NET/C# developers who want to
build on ICP using Blazor WebAssembly. This template fills that gap by providing
a working starter project that combines Blazor WASM (.NET 10) on the frontend with
a Motoko canister on the backend, using icp-cli for deployment. Without this template,
.NET developers face undocumented pitfalls that make getting started unnecessarily
difficult.

Requirements

• Blazor WASM frontend that successfully calls a Motoko backend canister
• Uses icp-cli with canister.yaml configuration (not dfx)
• Works on local network and mainnet
• Documents all known gotchas specific to Blazor + ICP
• No JS interop race conditions between @dfinity/agent and Blazor runtime
• Canister ID discovery via ic_env cookie without hardcoding

Considered Solutions

1. ES module script (type="module") for @dfinity/agent — rejected due to browser
   deferral behavior causing a race condition where Blazor attempts JS interop before
   the module is ready, silently breaking button events.
2. Webpack bundle loaded with defer — selected. Compiles @dfinity/agent into a
   single plain JS file exposed as window.IcpAgent. The defer attribute guarantees
   script execution order before DOMContentLoaded, so the global is always available
   when Blazor makes its first JS interop call.

Recommended Solution
Webpack + defer loading pattern, modeled after the existing Dfinity.Blazor
community library. This is the only approach that reliably solves the JS interop
race condition without adding complexity to the Blazor startup sequence. It also
bundles @dfinity/agent locally (no CDN dependency), pins the version in package.json,
and produces a single minified file that the asset canister can certify correctly.

Considerations

• Security: No impact. The template follows the same trust model as other icp-cli
  templates — no private keys, no hardcoded canister IDs.
• Performance: The webpack bundle adds ~271KB (uncompressed) to the frontend assets.
  This is negligible compared to the Blazor WASM runtime (~5MB+). Brotli compression
  via the asset canister reduces the bundle to ~80KB on the wire.
• Users: Purely additive. Existing templates are unaffected. .NET developers gain
  a working starting point without having to discover undocumented pitfalls.
• Breaking changes: None.
• Maintenance: Low. The template depends on @dfinity/agent and the @dfinity/motoko
  recipe — both of which are maintained by DFINITY. The .NET 10 LTS support window
  runs until November 2028, so no forced upgrade in