feat(telemetry): session-telemetry seam with mandatory redaction + OTel backend

Revive the reviewed session-telemetry packages from the closed
session-telemetry-otlp-rfc branch (PR #222/#231) on current master, renamed
to @deepseek-ai/dsh-session-telemetry{,-otel} (the SDK component-telemetry
package holds the dsh-telemetry name).

Delta over the branch version: every record now passes a telemetry/redact
waterfall between projection and emit() — the innermost next() applies a
non-configurable conservative credential-shape rule set, listeners stack
stricter rules, a throwing rule withholds the record fail-closed, and the
canonical log is never rewritten. This answers the export-side concern that
closed PR #222; the boundary axiom (our aspect ends at emit(); delivery is
the reporting SDK's) is unchanged, and the runtime-telemetry RFC's outbox /
readCommitted lane is recorded as deferred in the Agent Note.

Covered by seam/redact/OTel-wire unit tiers (100% per-file) and a keyless
Loader-composition e2e that boots the examples fixture against a mock OTLP
collector and pins redaction on the wire plus the untouched canonical log.

scripts/gen-doc-graphs.ts

@@ -77,6 +77,7 @@ const GROUP_ORDER = [
   'session-persistence',
   'session-query',
   'session-title',
+  'telemetry',
   'support',
   'ui',
 ]
@@ -132,6 +133,15 @@ const SERVICE_ROLES: ServiceRole[] = [
     consumers: ['agent-loop', 'tool-bash', 'hooks-claude', 'hooks-codex', 'acp', 'session-query', 'session-query-sqlite'],
     note: 'Backends persist the same SessionEvent vocabulary; apps choose a backend at composition time.',
   },
+  {
+    key: 'telemetry',
+    pkg: 'session-telemetry',
+    title: 'Session telemetry seam',
+    mode: 'seam',
+    implementations: ['session-telemetry-otel'],
+    consumers: [],
+    note: 'The seam captures, redacts, and hands session records to one backend; nothing else consumes the service — its output leaves the process.',
+  },
   {
     key: 'sessionQuery',
     pkg: 'session-query',