Make raiseIntent context argument optional

[Roaders]

The context argument of raiseIntent is now optional (context?: Context | null). Apps that only raise an intent to obtain a result no longer need to pass the fdc3.nothing context explicitly.

When context is omitted (or null/undefined is passed) the Desktop Agent proxy substitutes the fdc3.nothing context type, so the wire protocol is unchanged, the IntentHandler is untouched, and intent listeners always receive a concrete context. This is an additive, non-breaking change for TypeScript applications.

• fdc3-standard: make context optional/null on the DesktopAgent interface and update the JSDoc and examples
• fdc3-agent-proxy: substitute fdc3.nothing when no context is provided
• website docs: mirror the interface change
• tests: add proxy scenarios for the no-context and null-context cases
• CHANGELOG: add entry under [Unreleased] > Changed

Describe your change

Related Issue

resolves #1708

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• I acknowledge that a contributor license agreement is required and that I have one in place or will seek to put one in place ASAP.

Review Checklist

• Issue: If a change was made to the FDC3 Standard, was an issue linked above?
• CHANGELOG: Is a CHANGELOG.md entry included?
• API changes: Does this PR include changes to any of the FDC3 APIs (DesktopAgent, Channel, PrivateChannel, Listener, Bridging)?
  • Docs & Sources: If yes, were both documentation (/docs) and sources updated?
    
    JSDoc comments on interfaces and types should be matched to the main documentation in /docs
  • Conformance tests: If yes, are conformance test definitions (/toolbox/fdc3-conformance) still correct and complete?
    
    Conformance test definitions should cover all required aspects of an FDC3 Desktop Agent implementation, which are usually marked with a MUST keyword, and optional features (SHOULD or MAY) where the format of those features is defined
  • Schemas: If yes, were changes applied to the Bridging and FDC3 for Web protocol schemas?
    
    The Web Connection protocol and Desktop Agent Communication Protocol schemas must be able to support all necessary aspects of the Desktop Agent API, while Bridging must support those aspects necessary for Desktop Agents to communicate with each other
    • If yes, was code generation (npm run build) run and the results checked in?
      
      Generated code will be found at /src/api/BrowserTypes.ts and/or /src/bridging/BridgingTypes.ts
• Context types: Were new Context type schemas created or modified in this PR?
  • Were the field type conventions adhered to?
  • Was the BaseContext schema applied via allOf (as it is in existing types)?
  • Was a title and description provided for all properties defined in the schema?
  • Was at least one example provided?
  • Was code generation (npm run build) run and the results checked in?
    
    Generated code will be found at /src/context/ContextTypes.ts
• Intents: Were new Intents created in this PR?
  • Were the intent name prefixes and other naming conventions & characteristics adhered to?
  • Was the new intent added to the list in the Intents Overview?

[netlify]

❌ Deploy Preview for fdc3 failed. Why did it fail? →

Name	Link
🔨 Latest commit	07aaa53
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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.48%. Comparing base (31f79d4) to head (07aaa53).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1983   +/-   ##
=======================================
  Coverage   95.48%   95.48%           
=======================================
  Files          85       85           
  Lines        6705     6711    +6     
  Branches      818      897   +79     
=======================================
+ Hits         6402     6408    +6     
  Misses        303      303           

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[julianna-ciq]

lgtm