feat: add npm/yarn/pnpm install output filter

[bug-ops]

Parent: #717

Problem

npm install produces verbose download/resolution output. yarn and pnpm have similar noise.

Acceptance Criteria

• Match npm install, npm ci, yarn install, yarn add, pnpm install, pnpm add
• Strip package resolution/download progress lines
• Preserve audit warnings, peer dependency conflicts, and errors
• Show summary: packages added/removed count
• Config: [tools.filters.npm] with enabled flag
• Tests with realistic output samples
• Expected savings: 85-95%

[bug-ops]

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