feat: separate telemetry eligibility denominators

[kforris]

Summary

• add backward-compatible telemetry contract v2 for adoption and semantic writeback
• report explicit numerator, eligible denominator, exclusions, unobservable Codex tasks, and reason counts
• label contract-v1 history without rewriting semantic payloads
• expose matching API, MCP, Inspector, and English/Chinese documentation surfaces
• release source metadata as 0.7.3 with plugin payload 0.7.3+codex.c8d9b1c8b2bf

Acceptance evidence

• Node: 60 passed, 10 environment-gated skips
• temporary PostgreSQL 17: 10 passed, including semantic, lifecycle, read-only, legacy implicit, hook/MCP, and unobservable fixtures
• Swift: 5 passed plus release build
• TypeScript, build, formatting, plugin cache key, npm package dry-run: passed
• full and production npm audit: 0 vulnerabilities
• authenticated local Inspector visual and Refresh interaction: passed

Compatibility and risk

• old top-level mixed adoption fields remain unchanged for older clients
• migration 010 adds labels/defaults only; historical semantic payloads are not rewritten
• public release, Marketplace submission, payment, and marketing remain out of scope