fix: update stale org links, remove vendored non-project docs

- Repoint every Stellar-Insightss/* and bare Stellar-inights reference
  to Stellar-Analysis/* across workflows, docs, and in-code comments.
  Includes an onboarding doc that was pointing new contributors at a
  personal fork instead of the org repo.
- Remove 405 files under docs/ that are vendored copies of other
  projects' documentation with no connection to this project: the
  Next.js framework docs (274, identified by their `---` frontmatter),
  eslint-plugin-jsx-a11y's rule pages (85, `end auto-generated rule
  header` marker), undici's docs (41), date-fns's docs (4), and a
  threat model for an unrelated npm package called `resolve` (1).
  Verified against every known project-specific doc first so none of
  those were caught. Leaves the ~99 project-specific docs/*.md files
  and the adr/, architecture/, testing/, debugging/, issues/, and
  grafana/ subfolders untouched.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BRDH4c1gieXvgcMREtazSR

Author: christabel888

.github/workflows/contract-fuzzing.yml

@@ -24,8 +24,8 @@ jobs:
         run: |
           test ! -d contracts
           test -f docs/contract-invariants.md
-          grep -q 'Stellar-Insightss/contracts' docs/contract-invariants.md
+          grep -q 'Stellar-Analysis/contracts' docs/contract-invariants.md
       - name: Explain the contract quality gate
         run: |
-          echo 'Property tests, fuzzing, and contract coverage run in Stellar-Insightss/contracts.'
+          echo 'Property tests, fuzzing, and contract coverage run in Stellar-Analysis/contracts.'
           echo 'See docs/contract-invariants.md for the per-contract safety invariants.'