Add sticky_threshold and sticky_override to router decision API

[aashna]

Support threshold-based sticky routing to prevent mid-conversation model switching on low-confidence predictions.

Changes:

• Add sticky_override bool to RouterDecisionResponse interface and validator
• Add optional sticky_threshold parameter to getRouterDecision()
• Send sticky_threshold in request body when provided
• Log sticky_override in trace output and request logger markdown
• AutomodeService logs sticky override events for observability

[Copilot]

Pull request overview

This PR updates the auto-mode router decision client contract to support “sticky routing” by (a) optionally sending a sticky_threshold to the router API and (b) consuming/logging a sticky_override flag in the router response for improved traceability and observability.

Changes:

• Extend RouterDecisionResponse to include sticky_override and update response validation accordingly.
• Add optional stickyThreshold to getRouterDecision() and include sticky_threshold in the request body when provided.
• Log sticky_override in router trace output / request logger markdown, and emit an AutomodeService trace when sticky override occurs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/platform/endpoint/node/routerDecisionFetcher.ts	Adds sticky_override to the response contract/validator, adds optional stickyThreshold request parameter, and logs sticky routing data in trace + request logger output.
src/platform/endpoint/node/automodeService.ts	Logs sticky override events when the router indicates a sticky routing override occurred.