feat(scan): generation progress and quiet mode on scan helpers

[davidberenstein1957]

Feature Request

Show progress (or structured logs) while generate_suite runs, label scan phases (generating vs running), and add a verbose switch on quality_scan / vulnerability_scan so CI can suppress Rich UI and print_report while still returning SuiteResult.

Motivation

Suite.run already has Rich progress. Generation (adversarial LLM + HF downloads) can take minutes with no feedback. Scan helpers always print reports. Opt-in check-level logging (#2607) does not cover generation or a first-class quiet API.

Implementation plan

1. generate_suite: Rich progress (or logging INFO) over generators — i/n + generator class/name; update on completion/failure.
2. Scan helpers: set phase before generate vs run; pass verbose into Suite.run (existing flag) and gate result.print_report().
3. Non-TTY: fall back to log lines (no broken Rich escape codes in CI).
4. Complement feat(checks): opt-in progress logging for scenario/check execution (#… #2607; do not replace logging.
5. Tests with spies: verbose=False never calls print_report; fake multi-generator suite emits ≥1 progress/log event during generate.

API usage

from giskard.scan import generate_suite, vulnerability_scan

# Interactive (default): progress + printed report
result = await vulnerability_scan(
    target=my_agent,
    description="...",
    languages=["en"],
    verbose=True,  # default
)

# CI / captured logs: no Rich suite bar, no print_report
result = await vulnerability_scan(
    target=my_agent,
    description="...",
    languages=["en"],
    verbose=False,
)
assert result.passed is False or True  # still a SuiteResult
print(result.pass_rate)  # inspect programmatically

# Generation only
suite = await generate_suite(
    description="...",
    languages=["en"],
    max_scenarios=20,
    verbose=True,
)

Example terminal output (verbose generate)

Generating suite  [2/7] AdversarialScenarioGenerator
Generating suite  [3/7] GOATAttackScenarioGenerator
Generated 36 scenarios.
Running suite …
████████████░░░░  18/36  pass=14 fail=3 error=1

Example log lines (non-TTY / verbose generate)

INFO giskard.scan.catalog: generate_suite: start generators=7 max_scenarios=40
INFO giskard.scan.catalog: generate_suite: done generator=AdversarialScenarioGenerator scenarios=12
INFO giskard.scan.catalog: generate_suite: finished total_scenarios=36
INFO giskard.scan: vulnerability_scan: phase=running scenarios=36

Quiet mode (verbose=False)

No Rich bars, no automatic print_report(). Return value unchanged:

SuiteResult(scenarios=[...], ...)  # same type as today

Acceptance criteria

• generate_suite alone is not a silent multi-minute hang
• Scan helpers accept verbose and can suppress print_report
• Tests cover quiet mode + at least one generation progress/log event

Out of scope

• Token / cost aggregation (separate)
• Changing default scenario budgets

[linear-code]

OSS-107