[product-manager-impersonator] Workflow-call switch for no-op issue noise

## Feature Idea

**Summary:** Add a reusable-workflow input to control whether `noop` results are reported as issues, so high-frequency scheduled workflows can reduce noise without changing core behavior.

## Why a Customer Would Want This
Teams running many scheduled detectors get large volumes of successful no-op reports, which makes it harder to spot actionable failures and regressions. They need a caller-level switch to keep signal high while still using the same workflows.

## Rough Implementation Sketch
- Add a boolean `report-noop-as-issue` input (default `true`) to shared scheduled reusable workflows (for example, `gh-aw-scheduled-audit.md` and detector workflows built on it).
- Wire that input into `safe-outputs.noop.report-as-issue` in workflow sources.
- Keep defaults unchanged so existing consumers see no behavior change.
- Document the input in workflow READMEs/example usage and the catalog docs.

## Why It Won't Be That Hard
The repository already supports `report-as-issue: false` in workflow frontmatter and already has standardized `workflow_call` input plumbing; this is mostly additive wiring + docs across existing workflow templates.

## Evidence
- Scheduled workflow usage is broad in the docs catalog: `docs/workflows/gh-agent-workflows.md:67-101`.
- Detector docs repeatedly state that most runs end with `noop`:
- `docs/workflows/gh-agent-workflows/bugs.md:5`
- `docs/workflows/gh-agent-workflows/code-complexity.md:5`
- `docs/workflows/gh-agent-workflows/code-duplication.md:5`
- `docs/workflows/gh-agent-workflows/test-coverage.md:5`
- Reusable workflow inputs currently have no no-op reporting control:
- `.github/workflows/gh-aw-bug-hunter.md:24-54`
- `.github/workflows/gh-aw-scheduled-audit.md:22-60`
- The no-op reporting switch already exists at frontmatter level (proves feasibility): `.github/workflows/gh-aw-duplicate-issue-detector.md:64-67`.
- Current no-op aggregation is noisy in practice: issue `#765` (`[aw] No-Op Runs`) has 162 comments as of 2026-04-13.
- Related but distinct request: `#864` covers **failure-issue** reporting, not **noop** reporting.

> [!NOTE]
>
> 🔒 Integrity filter blocked 1 item
>
> The following item were blocked because they don't meet the GitHub integrity level.
>
> - [#392](https://github.com/elastic/ai-github-actions/pull/392) `list_pull_requests`: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
>
> To allow these resources, lower `min-integrity` in your GitHub frontmatter:
>
> ```yaml
> tools:
> github:
> min-integrity: approved # merged | approved | unapproved | none
> ```
>
>

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[What is this?](https://ela.st/github-ai-tools) | [From workflow: Trigger Product Manager Impersonator](https://github.com/elastic/ai-github-actions/actions/runs/24394014787)

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