A neighbour list is bounded per entry, and a hub is surfaced

[sameera]

As a contributor running the concept validator, I want each integration bullet bounded and
unusually connected pages reported without failing the run, so that the neighbour list cannot
grow without limit now that it sits outside the cap, and a genuine hub still gets reviewed.

Acceptance Criteria

• Given an Integration Points bullet longer than the hard ceiling, when the validator
  runs, then the bullet is reported and the run exits non-zero.
• Given every Integration Points bullet in the store at the time of the change, when the
  validator runs, then none is over the hard ceiling.
• Given a bullet over the advisory threshold but under the hard ceiling, when the
  validator runs, then it is reported and the run still exits zero.
• Given the store's highest-degree page, when the validator runs, then a
  high-degree advisory names it and the run still exits zero.
• Given a run whose only findings are advisories, when it completes, then the
  advisories are distinguishable in the output from findings that fail the run.

Notes

• story_type: system · size: S

The advisory must not fail the run: the highest-degree page today carries 15 edges and is
legitimately a hub, so a blocking degree limit would fail the store on day one and violate the
no-edits success metric.

Exiting zero is necessary but not sufficient — the drain currently treats any printed finding as
blocking, so #224 must teach it the difference. Depends on #221 fixing both
integers; until then the thresholds are unverifiable.