[Condense] Track telemetry for condense and truncate operations

[canrobins13]

Related GitHub Issue

Closes: #3674

Description

Adds telemetry for the new condense and truncate features

Test Procedure

Tried triggering manual condense operation and confirmed no bugs. I'm not sure where to look for the telemetry output though.

Type of Change

• 🐛 Bug Fix: Non-breaking change that fixes an issue.
• ✨ New Feature: Non-breaking change that adds functionality.
• 💥 Breaking Change: Fix or feature that would cause existing functionality to not work as expected.
• ♻️ Refactor: Code change that neither fixes a bug nor adds a feature.
• 💅 Style: Changes that do not affect the meaning of the code (white-space, formatting, etc.).
• 📚 Documentation: Updates to documentation files.
• ⚙️ Build/CI: Changes to the build process or CI configuration.
• 🧹 Chore: Other changes that don't modify src or test files.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Code Quality:
  • My code adheres to the project's style guidelines.
  • There are no new linting errors or warnings (npm run lint).
  • All debug code (e.g., console.log) has been removed.
• Testing:
  • New and/or updated tests have been added to cover my changes.
  • All tests pass locally (npm test).
  • The application builds successfully with my changes.
• Branch Hygiene: My branch is up-to-date (rebased) with the main branch.
• Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
• Changeset: A changeset has been created using npm run changeset if this PR includes user-facing changes or dependency updates.
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

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Important

Add telemetry tracking for condense and truncate operations, capturing context condensation and sliding window truncation events.

• Telemetry:
  • Add captureContextCondensed and captureSlidingWindowTruncation methods in TelemetryService.
  • Track CONTEXT_CONDENSED and SLIDING_WINDOW_TRUNCATION events in PostHogClient.
• Functions:
  • Update summarizeConversation in index.ts to capture CONTEXT_CONDENSED event.
  • Update truncateConversation in index.ts to capture SLIDING_WINDOW_TRUNCATION event.
• Tests:
  • Add taskId parameter to summarizeConversation and truncateConversation calls in index.test.ts and sliding-window.test.ts.
  • Update Task.ts to pass taskId to summarizeConversation and truncateConversationIfNeeded.

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[mrubens]

Could we add some way to distinguish between automatic and manual?