ci: skip functions workflow on doc-only changes

[Ankitsinghsisodya]

Problem

The Functions CI workflow runs the full suite — unit tests across 5 OSes, template tests, integration tests, and a 7-runtime E2E matrix — even when a PR only touches documentation or non-code files (*.md, docs/**, CODEOWNERS, LICENSE). This wastes CI minutes and runner time.

Proposed Solution

Add paths-ignore filters to the push and pull_request triggers so the workflow is skipped when only documentation or non-code files are modified.

[Ankitsinghsisodya]

/assign