chore(docs): unify patterns/ naming to NN-slug[-walkthrough].md

[trilamsr]

Summary

Patterns 1-5 in docs/patterns/ carried pattern-N-slug.md while
patterns 7-13 used the lexsort-stable NN-slug.md prefix — two schemes
side-by-side. Pattern #2 carried both an engineering design spec
(02-ib-link-flap.md) AND an operator walkthrough
(pattern-2-ib-link-flap.md); these look like dup-naming but are
intentionally distinct doc types per the docs/patterns/README.md
two-table split (operator walkthroughs vs. design specs / TDD red-test
inputs).

This PR unifies the numeric-prefix scheme across the directory while
preserving the spec/walkthrough type distinction via a filename suffix:

• NN-slug.md = engineering design spec
• NN-slug-walkthrough.md = operator-facing runbook

Renames (5)

Old	New
pattern-1-nvlink-degradation.md	01-nvlink-degradation-walkthrough.md
pattern-2-ib-link-flap.md	02-ib-link-flap-walkthrough.md
pattern-3-hbm-ecc.md	03-hbm-ecc-walkthrough.md
pattern-4-thermal-throttle.md	04-thermal-throttle-walkthrough.md
pattern-5-pcie-aer.md	05-pcie-aer-walkthrough.md

Pattern #2 dup investigation (not a dup)

02-ib-link-flap.md (engineering design spec) and
pattern-2-ib-link-flap.md (operator walkthrough with PromQL alert

• escalation runbook) are distinct doc types that cross-reference
  each other. docs/patterns/README.md already lists them in separate
  tables (operator walkthroughs vs design specs). Both retained;
  walkthrough renamed to 02-ib-link-flap-walkthrough.md per the
  unified convention.

recipes-path-check*.sh retained (not the dup-scheme validator)

The original task plan flagged scripts/recipes-path-check.sh +
_test.sh for deletion as "the validator policing both schemes".
On inspection: those scripts implement the issue #427 convention
gate that lints commit subjects / PR titles for references to a
non-existent recipes/pattern-N/ directory layout. They have
nothing to do with docs/patterns/ filenames. Retained.

Inbound-ref updates (9 files)

• docs/MILESTONES.md, docs/NORTHSTARS.md
• docs/integrations/prometheus-scrape.md
• docs/rfcs/0014-metrics-to-logs-pattern-input.md
• docs/followups/M4b.md (forward-ref to planned
  14-pod-evicted-walkthrough.md)
• docs/patterns/README.md (table rows + new "Filename convention"
  section documenting the NN- / NN-walkthrough split)
• docs/patterns/02-ib-link-flap.md (spec's cross-link to its
  walkthrough)
• module/pkg/patterns/{hbm_ecc,thermal_throttle,pcie_aer}.go
  (doc-comment references)
• module/pkg/replay/thermal_throttle/canonical/manifest.json
  (replay-fixture description text)

Why this shape (vs collapsing both schemes into one)

The original task framing assumed the two schemes were unintended
divergence — but the README's two-table layout treats them as a
deliberate audience split (engineering TDD-spec readers vs.
operators triaging incidents). Collapsing the walkthroughs into the
spec namespace would have destroyed that signal. The
-walkthrough suffix preserves the semantic distinction while
giving the directory the lexsort-stable numeric prefix the task
wanted.

Test plan

• make doc-check exit 0 pre-change (217 anchors + 1105
  markdown links + 239 non-md intra-repo links resolve)
• make doc-check exit 0 post-change (same counts; zero
  broken refs introduced)
• rg 'pattern-[1-5]-' docs/ install/ .github/ module/ scripts/
  returns only in-page heading anchors (#pattern-2--…,
  #m17-pattern-1-…), no stale filename refs
• Pre-commit hook: attribute-namespace-check clean (100
  attributes documented), slo-rules-check 13 rules OK,
  chart-appversion-check matches, all module verify pass
• Pre-push hook: no-autoupdate-check_test clean

docs: unify `docs/patterns/` filename convention to a single
`NN-slug.md` / `NN-slug-walkthrough.md` scheme. Operator walkthroughs
for patterns 1-5 renamed; design-spec files keep the `NN-slug.md`
shape; pattern #2 retains both (spec + walkthrough).