feat: add yq rewrite rule and TOML filter for YAML query output compression

Problem

yq is the YAML counterpart to jq — it produces verbose YAML output that can be large when querying multi-document manifests, Kubernetes configs, or Helm values files. Currently rtk has no hook rewrite rule for yq, so bare yq commands are never compressed even though a simple truncation filter would save significant tokens.

Proposed Solution

Add a yq rewrite rule to src/discover/rules.rs and create src/filters/yq.toml following the same pattern as the existing jq.toml:

• match_command = "^yq\\b"
• strip_lines_matching = ["^\\s*$"] — remove blank lines
• max_lines = 40
• truncate_lines_at = 120

Related

• Similar to #1364 (jq rewrite rule) — same compression pattern for structured query tools
• jq.toml already exists as the template for this approach