docs: CHANGELOG token savings name the per-skill skip and the autoplan follow-up (ship review pass 2)

The pointer's skip is bound to the skill's own copy of sections/preamble.md,
so "every later one saves about 5,800" holds per skill, not per session, and
/autoplan's skip list and the inline /office-hours loader do not yet skip the
pointer section. The entry now says so instead of claiming the full /autoplan
saving. Adding the skip entry grows size-pinned skills, so it is a follow-up.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## [Unreleased]
 
-**Tier 2+ skills load the shared preamble once per session instead of once per invocation.** Every tier 2+ SKILL.md carried the same ~23 KB of preamble (AskUserQuestion format, voice, writing style, completeness, completion protocol and more), so each skill invocation re-read text the conversation already held. That text now renders once per host into `sections/preamble.md` beside each tier 2+ SKILL.md. The SKILL.md keeps a short "Shared preamble (load first)" pointer naming the file and its content id, and asks for the Read unless the skill's own earlier Read of that file, headed by that id, is still in context, so other text that merely carries the id cannot stand in for the shared rules. Measured with Anthropic token counting: review's SKILL.md drops from 21,884 to 16,103 tokens, ship from 22,688 to 16,907, office-hours from 27,100 to 23,085 and design-review from 39,040 to 33,261. The shared file is 5,953 tokens, so a session's first invocation costs about 170 tokens more than before (about 1,900 for office-hours, about 3,800 for plan-eng-review) and every later one saves about 5,800 (4,000 for office-hours, 2,200 for plan-eng-review). A /autoplan run over all four review phases reads 17,941 fewer tokens (191,871 → 173,930), because its review-skill methodology loads no longer repeat the preamble.
+**Tier 2+ skills load the shared preamble once per session instead of once per invocation.** Every tier 2+ SKILL.md carried the same ~23 KB of preamble (AskUserQuestion format, voice, writing style, completeness, completion protocol and more), so each skill invocation re-read text the conversation already held. That text now renders once per host into `sections/preamble.md` beside each tier 2+ SKILL.md. The SKILL.md keeps a short "Shared preamble (load first)" pointer naming the file and its content id, and asks for the Read unless the skill's own earlier Read of that file, headed by that id, is still in context, so other text that merely carries the id cannot stand in for the shared rules. Measured with Anthropic token counting: review's SKILL.md drops from 21,884 to 16,103 tokens, ship from 22,688 to 16,907, office-hours from 27,100 to 23,085 and design-review from 39,040 to 33,261. The shared file is 5,953 tokens, so a skill's first invocation in a session costs about 170 tokens more than before (about 1,900 for office-hours, about 3,800 for plan-eng-review) and every later invocation of that skill saves about 5,800 (4,000 for office-hours, 2,200 for plan-eng-review). The skip is tied to the skill's own copy of the file, so the first invocation of each different skill pays the Read again. A /autoplan run's four review-skill loads carry 17,941 fewer SKILL.md tokens (191,871 → 173,930), but /autoplan's section skip list and the inline /office-hours loader do not yet name the "Shared preamble (load first)" section, so each loaded skill can still ask for its own shared file; adding it grows size-pinned skills and is a follow-up.
 
 ### Changed
 - **`scripts/resolvers/preamble-hoist.ts`** (new) renders `{{PREAMBLE}}` for tier 2+ skills: a section moves to the shared file only when this skill's render of it is byte-identical to the shared render, so no skill's instructions change. Sections that name the skill (the start command, Question Tuning, Repo Ownership, Search Before Building, Telemetry), text without its own heading, and skill-specific variants stay inline; a variant that keeps the shared subsection headings carries only its differing `###` subsections. Tier 1 skills keep their short preamble inline. Across all 41 hoisted skills, the SKILL.md with its shared file applied holds exactly the paragraphs the pre-hoist SKILL.md held.