docs: strip dead docs/superpowers/ refs across ADRs + guides + glossary

The docs/superpowers/{specs,plans}/ directory was archived to .archive/
in an earlier session (and .archive/ is gitignored). Every md link
into that path is now a broken reference for anyone consuming the
template fresh.

Stripped:
  - ADR-011: **Spec:** header line
  - ADR-015: **Spec:** + **Plan:** header lines
  - ADR-016: **Spec:** + **Plan:** header lines + footer "Spec —"
    bullet (the design rationale is captured in the ADR body itself)
  - ADR-017: **Spec:** + **Plan:** header lines
  - ADR-018: **Spec:** + **Plan:** header lines
  - guides/realtime.md: inline "the full spec" link + footer
    [Spec] entry (folded its description into the ADR-016 entry)
  - guides/events-and-jobs.md: inline "the full spec" link
  - architecture/vertical-feature-spec.md: stale "Deleted" subsection
    referencing docs/superpowers/plans/*

Updated:
  - glossary.md "PRD" entry: clarified status flow now matches the
    shipped pnpm work prd-ship lifecycle (draft -> in-review ->
    approved -> shipped); removed the parenthetical pointing at
    docs/superpowers/specs/ as a definition of "spec"
  - glossary.md "spec" flagged-ambiguity: rewritten to reflect that
    durable design lives in ADRs (docs/decisions/adr-NNN-*.md) and
    implementation seeds live in PRDs (docs/work/prds/*.prd.md) —
    "spec" should be avoided in this template

Preserved (legitimate refs to the SuperPowers plugin, not the dir):
  - agent-first-workflow-and-conformance.md mentions of
    `superpowers:brainstorming` — these reference the external
    plugin skill, not a file in the repo

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/decisions/adr-017-opentelemetry-migration.md

@@ -2,8 +2,6 @@
 
 **Status:** Accepted
 **Date:** 2026-05-11
-**Spec:** docs/superpowers/specs/2026-05-11-opentelemetry-migration-design.md
-**Plan:** docs/superpowers/plans/2026-05-11-opentelemetry-migration.md
 **Supersedes (impl section):** ADR-014
 
 ## Context
@@ -37,12 +35,14 @@ This ADR migrates the substrate to OpenTelemetry: code emits OTel spans, logs, a
 ## Consequences
 
 **Positive:**
+
 - Vendor swaps are exporter swaps. Adding Honeycomb / Datadog / Grafana Cloud / Tempo is just adding their exporter alongside Sentry's.
 - Auto-instrumentations (HTTP, undici, pg) reduce manual span boilerplate.
 - New `IMetrics` signal available; metrics call sites can land per-feature opportunistically.
 - PII scrubbing is vendor-neutral — applies before any exporter sees the data.
 
 **Negative:**
+
 - Sentry-native error UX is slightly degraded (errors arrive as OTel log records instead of native Sentry events). Acceptable per vendor-neutrality goal.
 - Breadcrumb semantics shift from buffered cross-span to per-span events. Acceptable.
 - Browser is still Sentry-direct — observability stack is asymmetric server vs. browser until a future browser migration.