ci(docs): always trigger docs workflow on PRs; move filtering into workflow

[thinkall]

Why

Today the docs workflow uses trigger-level paths filters. When a PR doesn't touch any of those paths, GitHub never starts the workflow, so the docs check is reported as expected but not run — which can leave required-status-check rules waiting indefinitely and makes branch-protection harder to manage.

What

• Drop the paths filters from both the pull_request and push triggers so the workflow always starts on PRs (and on pushes to main) and reliably reports a check status.
• Add a changes job that uses dorny/paths-filter@v3 to detect doc-related changes inside the workflow, with recursive globs:
  • flaml/**
  • website/**
  • .github/workflows/deploy-website.yml
• Gate the existing checks and gh-release jobs on needs.changes.outputs.docs so the heavy build/deploy steps are still skipped when nothing relevant changed (preserving today's compute behavior).
• workflow_dispatch (and merge_group for checks) can still force a run regardless of the filter.

The previous flaml/* / website/* patterns only matched files in the top of those directories — switching to ** ensures changes anywhere in the tree are picked up.

Behavior matrix

Event	changes	checks	gh-release
pull_request	always	runs only if doc files changed	never
push to main	always	never	runs only if doc files changed
workflow_dispatch	always	always	always
merge_group	always	always	runs only if doc files changed

[Copilot]

Pull request overview

Adjusts the docs GitHub Actions workflow so it always triggers on PRs/pushes (avoiding “expected but not run” required-check deadlocks) while keeping expensive docs build/deploy steps conditional on doc-related file changes detected inside the workflow.

Changes:

• Removed trigger-level paths filters so the workflow always starts on pull_request and push to main.
• Added a changes job using dorny/paths-filter@v3 with recursive globs to detect doc-related changes.
• Gated checks and gh-release jobs on the changes job output (with overrides for workflow_dispatch / merge_group where applicable).