Use push events for IssueLens team memory

[Changyong Gong (chagong)]

Summary

• Migrate only .github/workflows/team-memory-post-merge.yml from pull_request_target: closed to pushes on main, preserving the required string workflow_dispatch input for single-PR recovery.
• Pin only the team-memory action to microsoft/IssueLens/.github/actions/issuelens@2b5317815e15179899014a02c41678620ce2d390, the merged Batch team-memory updates on default-branch pushes IssueLens#36 rollout. The action verifies all eligible merged PRs introduced by a push and submits one batch; pushes with no eligible merged PRs skip before Azure login. Manual dispatch remains the single-PR fallback.
• Require explicit team-memory enablement, the current default-branch ref, and a supported push/manual event. Key concurrency by push SHA, then manual PR number, then run ID; retain the existing repository/prefix and cancel-in-progress: false. Increase the timeout to 30 minutes.
• Preserve the runner, secrets, action inputs, activity/status privacy settings, empty top-level permissions, and job permissions (contents: read, pull-requests: read, id-token: write). No consumer checkout or local action is added. Issue-triage workflows and action pins, shared-wiki configuration, and policies are unchanged.

Validation

• Based on live main at b5be02bad36da1b60c9c14d976619ffc42f813e1; onboarding Onboard Java Debug Server to IssueLens #635 is merged.
• Passed actionlint 1.7.12 and strict YAML 1.2 parsing.
• Passed nine focused scratch tests, including an 840-case enablement/default-ref/supported-event truth table using @actions/expressions, exact trigger/pin/input/permission/timeout assertions, distinct push-SHA groups, stable same-PR manual groups, and repository/run-ID fallback checks.
• Self-reviewed the one-file diff; preservation assertions and git diff --check passed. Validation tooling and scratch tests remain outside the repository.

Rollout prerequisite and scope

Before rollout, verify that Azure OIDC federation accepts the default-branch subject repo:microsoft/java-debug:ref:refs/heads/main for push and manual dispatch (and the actual subject template if customized). Azure federation was not inspected or changed by this PR.

This is a caller-only migration and needs no Foundry deployment. No live workflow/agent invocation, deployment, Azure change, secret or repository-variable/policy change, or wiki write was performed. This PR does not merge or enable the workflow.