feat(protocol): add bounded list pagination

[SarthakWade]

Summary

• add reusable opaque cursor pagination to artifact, console, and network lists
• preserve deterministic ordering while rejecting expired, malformed, stale, cross-command, cross-filter, and cross-session cursors
• bound limits, cursor state, and encoded page values below the protocol frame ceiling
• publish typed CLI, protocol schema, TypeScript, Python, MCP, documentation, and both-engine E2E coverage

Security and compatibility

• cursor tokens are random server-side identifiers and contain no offsets, paths, filters, session names, page text, or secrets
• cursor records expire after five minutes, are capped at 512 entries per owning store, and disappear on restart
• collection mutations fail closed with typed recovery guidance instead of returning a misleading continuation
• callers that omit pagination options retain the prior first-page behavior and existing result fields

Validation

• pnpm test
• pnpm test:runtime
• pnpm test:npm
• Python pytest, mypy, ruff, and generated-contract checks
• web lint and production build
• production macOS app build
• focused WebKit and Chromium pagination flows, including stale, malformed, and wrong-filter failures
• shell syntax and generated-contract drift checks

Closes #195

[yashranaway]

Pagination for artifact.list, console.list, and network.list is fail-closed.

Cursors are random UUIDs stored in the owning process, not offsets in the token. They bind command/filter context, collection fingerprint, and direction, expire in five minutes, cap at 512 records, and vanish on restart. Unknown, expired, wrong-scope, and stale tokens are distinct errors. Limits are 1–250. Encoded page values stay under 768 KiB so the 1 MiB frame still has room for metadata. Default first-page behavior is preserved.

CI is green. Stacks on #199; merge 197 → 198 → 199 → 201.