🛡️ Harden quota tool redaction against Copilot scaffolding (issue #106) (#107)

* fix: 🐛 harden quota tool redaction against Copilot scaffolding

**🐛 Fixes**
- Detect quota failures only from real `LanguageModelToolResultPart` entries whose `callId` maps to a redactable tool. This prevents `<reminderInstructions>` and similar injected wrappers from stripping `insert_edit_into_file` on normal turns.
- Add confidence-aware redaction results so low-confidence matches are logged at DEBUG without emitting fake telemetry failures. Keep the request body unchanged and use confidence only for logging and telemetry.

**✅ Tests**
- Update the redaction tests to cover high-confidence tool-result matches, wrapper false positives, and non-redactable tool results. This verifies the detector no longer redacts on echoed prompt text.
- Adjust request builder test fixtures for the new confidence field.

**🧹 Chores**
- Bump the package version and add an Unreleased changelog entry for the fix.

* chore(release): publish 2.1.7 🏷️

**🧹 Chores**
- Add the `2.1.7` release notes to `CHANGELOG.md`, documenting the quota-redaction fix, test coverage updates, and telemetry cleanup. This keeps the published history aligned with the shipped behavior.
- Bump `package.json` from `2.1.7-dev1` to `2.1.7` so the extension is ready for release.