feat(gen): correct preamble tiers for the 8 silently-heaviest skills

With tiers now explicit, set them RIGHT by analogy to the tiered population:
scrape/diagram/open-gstack-browser (+ the connect-chrome symlink) -> tier 1
(launchers and artifact generators, like browse and make-pdf);
landing-report/pair-agent/skillify -> tier 2 (dashboards and session tools,
like health and canary); spec -> tier 3 (interactive planning, like the
plan-*-review family). Each tier-1 skill sheds 271 lines of onboarding
prose it never needed; tier-2 shed 20 each.

Verification per the review protocol: regen diff reviewed (pure
section-removal), skill-validation + size-budget + catalog-budget +
v0-dormancy suites green (822 tests), and live smoke of the tier-corrected
skills confirms the preamble renders the intended sections at each tier.
These skills have ~no eval coverage — stated honestly; the wave's gate-tier
eval run is the backstop.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

spec/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: spec
-preamble-tier: 4
+preamble-tier: 3
 version: 0.1.0
 description: Turn vague intent into a precise, executable spec in five phases. (gstack)
 allowed-tools:

spec/SKILL.md.tmpl

@@ -1,6 +1,6 @@
 ---
 name: spec
-preamble-tier: 4
+preamble-tier: 3
 version: 0.1.0
 description: |
   Turn vague intent into a precise, executable spec in five phases. Files the issue,