Consolidate the @peac/telemetry-otel package version to a single source
(packages/telemetry-otel/src/version.ts) and add a source-version-currency
gate so it cannot drift.

- provider.ts derived its tracer/meter version (emitted as the optional
  peac.version span/metric attribute) from a hardcoded 0.9.22 even though
  the package is 0.15.0. It now derives from the single version source, so
  the emitted value is correct and cannot drift. index.ts re-exports the
  same source.
- privacy.ts DEFAULT_SALT is unchanged (a stable hashing seed; changing it
  would alter every hashed identifier) with a clarifying comment.
- scripts/verify-doc-version-currency.mjs checks enumerated source sites
  (the telemetry version source and the smithery.yaml mcp-server pin)
  against docs/releases/current.json, plus an anti-drift guard that fails
  if the provider reintroduces a hardcoded version literal. It complements
  tests/tooling/docs-version-banner-truth.test.ts and does not duplicate
  the markdown-banner scan.
- tests/tooling/doc-version-currency.test.ts covers the pure checks and the
  CLI via a synthetic --root tree; import-smoke now asserts the version
  constant equals the package version.

No OpenTelemetry dependency or lockfile bump; no PEAC record/schema/wire/
signing/conformance change. Historical 0.9.22 references (CHANGELOG, the
architecture ADR, the privacy hash seed, and privacy filter-input test
fixtures) are left unchanged.