feat: add terraform plan/apply output filter

[bug-ops]

Parent: #717

Problem

terraform plan and terraform apply produce very verbose output with resource reading noise.

Acceptance Criteria

• Match terraform plan, terraform apply, tofu plan, tofu apply
• Strip Refreshing state... and Reading... lines
• Keep change summary (Plan: N to add, N to change, N to destroy)
• Keep resource change blocks (+ / - / ~ markers)
• Preserve errors
• Config: [tools.filters.terraform] with enabled flag
• Tests
• Expected savings: 70-90%

[bug-ops]

Resolved by PR #734: migrated to declarative TOML filter engine with built-in rule in default-filters.toml.