May bundle: deep-link audit (inline link specificity + verified VS Code anchors)

[briancl2]

Summary

Deep-link audit of every link in the May newsletter and the public cost bundle, plus a codified inline link-specificity policy and verifier. Follow-up to merged PR #23.

Policy: inline links whose label names a specific feature must point to the most specific deep/anchored source, not a generic landing/version page. Generic labels (Release Notes, VS Code Updates, month names) and aggregated Sources/References sections are exempt.

Changes

• .github/skills/newsletter-validation/SKILL.md: new Link Specificity (inline deep-link) section.
• .github/skills/newsletter-validation/scripts/validate_newsletter.sh: WARN-level shallow inline-link check (exempts generic labels + aggregated sections).
• reference/deep-research-report.md: scoped the prior stable-URL rule to KB/aggregated records; added the inline deep-link rule.
• output/2026-05_may_newsletter.md, release_bundle/.../NEWSLETTER_MAY_COST_SECTION.md, release_bundle/.../PUBLIC_SOURCES.md: repointed 45 shallow inline links to verified code.visualstudio.com/updates/v1_NNN#_<anchor> deep links, correcting several wrong-version links (e.g. tool search v1_119 -> v1_118#_tool-search-tool).

Verification

• All 152 unique external URLs return 200 (zero broken).
• validate_newsletter.sh: Inline links use deep/anchored sources PASS, PASSED (0 warnings).
• 23 anchored VS Code URLs each confirmed with the #_ anchor present in the live page.
• URL-masked diffs prove prose is unchanged; verbatim cost-section copy stays byte-identical to the newsletter line; shipped CUSTOMER_COMPANION.md link target untouched.
• No dollar/claim caveats modified.

Recorded as TH-29 / L189.