feat: PostHog product analytics (#58)

* wip: posthog analytics

* wip: remove posthog-rs crate; call endpoint directly

* make analytics non-blocking

* session start event

* configure analytics for release builds

* remove dev_server_stopped event

* address review comments

* simplify analytics enabled logic

* analytics on by default; send start_session when user enables analytics; new task_attempt_start event

* lower visibility of analytics logs

* chore: bump version to 0.0.37-0

* set analytics to true if previously unset

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Co-authored-by: GitHub Action <action@github.com>

.github/workflows/pre-release.yml

@@ -199,6 +199,8 @@ jobs:
           cargo build --release --target ${{ matrix.target }} --bin mcp_task_server
         env:
           CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER: ${{ matrix.target == 'aarch64-unknown-linux-gnu' && 'aarch64-linux-gnu-gcc' || '' }}
+          POSTHOG_API_KEY: ${{ secrets.POSTHOG_API_KEY }}
+          POSTHOG_API_ENDPOINT: ${{ secrets.POSTHOG_API_ENDPOINT }}
 
       - name: Setup Sentry CLI
         uses: matbour/setup-sentry-cli@v2