Python: Support list[str] arguments for file-based skill scripts (#5850)

Port of .NET PR #5475. Broadens the args type from dict[str, Any] | None
to dict[str, Any] | list[str] | None across the skill script API surface,
enabling CLI-style argv forwarding to subprocess scripts.

Changes:
- SkillScript.run(), InlineSkillScript.run(), FileSkillScript.run(): widen
  args type; InlineSkillScript rejects list with TypeError
- FileSkillScript.parameters_schema: returns array-of-strings schema
- FileSkill.content: appends <scripts> block with parameters_schema
- SkillScriptRunner protocol: widen args type
- SkillsProvider._run_skill_script: widen args type
- run_skill_script tool schema: accept object, array, or null
- subprocess_script_runner sample: accept list[str], reject dict
- class_based_skill sample: fix missing SkillFrontmatter wrapper
- Standardize 'folder' to 'directory' in docstrings (#5712)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/samples/02-agents/skills/class_based_skill/class_based_skill.py

@@ -10,7 +10,7 @@ import os
 # warnings.filterwarnings("ignore", message=r"\[SKILLS\].*", category=FutureWarning)
 from textwrap import dedent
 
-from agent_framework import Agent, ClassSkill, SkillsProvider
+from agent_framework import Agent, ClassSkill, SkillFrontmatter, SkillsProvider
 from agent_framework.foundry import FoundryChatClient
 from azure.identity import AzureCliCredential
 from dotenv import load_dotenv
@@ -49,10 +49,12 @@ class UnitConverterSkill(ClassSkill):
 
     def __init__(self) -> None:
         super().__init__(
-            name="unit-converter",
-            description=(
-                "Convert between common units using a multiplication factor. "
-                "Use when asked to convert miles, kilometers, pounds, or kilograms."
+            frontmatter=SkillFrontmatter(
+                name="unit-converter",
+                description=(
+                    "Convert between common units using a multiplication factor. "
+                    "Use when asked to convert miles, kilometers, pounds, or kilograms."
+                ),
             ),
         )