Add failing-case input variants to existing examples

[kmadan]

Goal

Each example under `examples/` currently ships one passing `input.json`. Add failing-case variants so newcomers can see what a non-compliant verdict looks like without editing the passing input.

Why this matters

Failing-case fixtures teach Rego deny paths and make the policy's actual guards obvious. They're also the easiest "first PR" for a new contributor.

Per-example additions

examples/eu-ai-act-transparency/

• `input-low-completeness.json` — documentation completeness below 0.7
• `input-high-toxicity.json` — toxicity above 0.7

examples/nist-ai-rmf-govern/

• `input-accountability-fail.json`, `input-transparency-fail.json`, `input-fairness-fail.json` — one per sub-function failure

examples/customer-support-llm/

• `input-above-threshold.json` — toxicity_score above the configured threshold

Acceptance criteria

• Each new input file demonstrates a non-compliant verdict when run through the example's policy
• Each example's README documents what each variant demonstrates
• Each example's `run.sh` accepts an optional input filename arg (e.g., `./run.sh input-low-completeness.json`) or a sibling `run-failing.sh` exists
• Optionally: matching `expected-output-*.json` files

Get help

Comment here. Splitting this across 3 PRs (one per example) is welcome.