fix(tools): Prevent broken skill tool references when prefix is set and support tool_filter

- Dynamic prefixing for load_skill, load_skill_resource, run_skill_script, and search_skills when toolset has a tool_name_prefix configured.
- Respect tool_filter in SkillToolset to correctly filter core and dynamic tools using the _is_tool_selected predicate.

TAG=agy
CONV=d82d2790-2c30-4d48-9d57-3c8f340280e2

Change-Id: I591065b097b03bc6dba5a9b3cb13ca95de62ed6b