docs(pipeline-crew): drop dead {#id} anchors from EXPLANATION.md, repoint HOW-TO links to GitHub auto-slugs (#3613)

[usirin]

What & why

claude-plugins/pipeline-crew/EXPLANATION.md declared four section anchors with Kramdown {#id} custom-anchor syntax. GitHub's markdown renderer does not honor {#id} — it drops the token and auto-generates its own slug from the heading text — so every in-repo deep link of the form EXPLANATION.md#<custom-id> resolved the file but jumped nowhere on GitHub (silent dead fragment). Scope is doc navigation only; no code path is affected.

Changes

• EXPLANATION.md — dropped the {#id} token from all four headings (roster law, §CP hard gate, verify-don't-relay, single-owner comms). GitHub now generates its own heading slugs.
• HOW-TO.md — repointed the four sibling deep links (landed via PR docs(pipeline-crew): plugin How-to — add a role · configure personalization · reboot · carry a §CP PR · retire a crew #3611) to GitHub's real auto-generated slugs, computed with github-slugger (the algorithm GitHub's renderer uses), not hand-guessed:
  • #roster-law → #the-roster-law--singleton-bridges-vs-a-fungible-engine (2 links)
  • #cp-gate → #the-cp-hard-gate--the-engine-banks-a-human-approves-the-pipeline-enqueues
  • #verify-dont-relay → #verify-dont-relay--a-claim-is-not-evidence-until-you-read-the-artifact

The fourth heading (single-owner comms) has no inbound link in the doc set, so no link update was needed for it.

Acceptance criteria

• The four headings in EXPLANATION.md no longer carry {#id} tokens.
• Every in-repo fragment link into those headings targets GitHub's auto-generated slug and resolves to the correct section.
• No {#id} custom-anchor syntax remains in the pipeline-crew doc set (grep clean).

Non-control-plane crew doc surface (founder ruling: all crew surfaces are non-§CP) — ship-on-green.

Fixes #3613

[usirin]

review-code: PASS @ 5902c5e — merge-ready

Verified PR #3617 against the acceptance criteria of #3613, one at a time (docs-only diff: claude-plugins/pipeline-crew/{EXPLANATION,HOW-TO}.md; class-probe routed it to review-code — crew docs under claude-plugins/pipeline-crew/ are neither the skills/agents subpath nor a has-docs surface, so they ride the no-class fail-closed to review-code). All files read from head 5902c5e645be769bde62fbf3ca8a59715ed2c75c via git show "$PR_REF:<path>", never the launched checkout.

• [PASS] The four EXPLANATION.md headings no longer carry {#id} custom-anchor tokens — headings at head render as plain ## The roster law — …, ## The §CP hard gate — …, ## Verify, don't relay — …, ## Single-owner human comms — …; grep for {# in EXPLANATION.md returns nothing.
• [PASS] Every in-repo fragment link into those headings targets GitHub's real auto-slug and resolves. The three inbound HOW-TO.md links were checked against the auto-slug computed by the github-slugger algorithm from the current heading text: #the-roster-law--singleton-bridges-vs-a-fungible-engine (HOW-TO.md:41,158), #the-cp-hard-gate--the-engine-banks-a-human-approves-the-pipeline-enqueues (:120), #verify-dont-relay--a-claim-is-not-evidence-until-you-read-the-artifact (:130) — each an exact match (double hyphen from the em-dash gap, §/comma/apostrophe stripped, correct). The fourth heading (single-owner comms) has no inbound link in the doc set, so nothing to repoint. No stale old-id link (#roster-law/#cp-gate/#verify-dont-relay/#single-owner-comms as a standalone anchor) survives.
• [PASS] No {#id} custom-anchor syntax remains anywhere in the pipeline-crew doc set — grep for {# across every file under claude-plugins/pipeline-crew/ at head is clean.

Run-evidence bundle: N/A — docs-only diff, no build/test surface; verified from the head files + github-slugger auto-slug computation.

Non-control-plane crew doc surface (founder ruling: all crew surfaces are non-§CP). All criteria pass. This PR is merge-ready. review-code does not merge — ship-it is the authorized merge step; merging will auto-close #3613 via Fixes #3613.