BUG: Jinja filters on a template parameter break when a YAML seed loads #4272

Describe the bug

When a YAML seed loads, SeedPrompt and SeedObjective render the template once with only the path variables. A filter on a parameter that isn't supplied yet runs on the placeholder. {{ prompt | upper }} turns into {{ PROMPT }}, so the later render with prompt=... fails with 'PROMPT' is undefined. {{ prompt | length }} turns into 0, and filters like replace or trim are just dropped.

default and the is tests already keep the template as it is (#3098), and so do filters that loop over the value, like join. Other filters don't.

Steps/Code to Reproduce

import tempfile
from pathlib import Path

from pyrit.models import SeedPrompt

for value in ["Say {{ prompt | upper }}", "{{ prompt | length }} characters"]:
    with tempfile.TemporaryDirectory() as folder:
        path = Path(folder) / "template.yaml"
        path.write_text(f"value: |-\n  {value}\nparameters:\n  - prompt\n")
        seed = SeedPrompt.from_yaml_file(path)

    print(f"loaded as {seed.value!r}")
    try:
        print("  rendered:", repr(seed.render_template_value(prompt="hello")))
    except ValueError as error:
        print("  render failed:", str(error).split(". Template")[0])

Expected Results

loaded as 'Say {{ prompt | upper }}'
  rendered: 'Say HELLO'
loaded as '{{ prompt | length }} characters'
  rendered: '5 characters'

Actual Results

loaded as 'Say {{ PROMPT }}'
  render failed: Error rendering template '<unnamed template>': 'PROMPT' is undefined
loaded as '0 characters'
  rendered: '0 characters'

None of the bundled templates put a filter on a parameter, so only custom ones run into this. A fix is to wrap every filter at load with the same deferral guard as default (_render_trusted_template_value in seed.py). I have it ready with a test and will open a PR.

Versions

• OS: macOS 26.4.1 (arm64)
• Python 3.13.16
• jinja2 3.1.6
• PyRIT main (fbef947)