docs: adopt shared ruleset rules in CLAUDE.md

[haribo]

Summary

Pastes the shared cross-project rule wordings verbatim into CLAUDE.md and records their adoption in .claude/rules.lock (issue #184). Part 1 (the ADR-lifecycle block) already landed in #178.

• Testing: red→green with "watch it fail"; the regression test references the issue number; evidence includes network capture.
• Documentation: refined code-is-not-source-of-truth / design-first; anchor a confirmed non-obvious decision in design/ADR before building on it.
• General: severe-opinion block (verdict-first, no flattery, challenge until the decision) + the artifact-verification rule (never assume a produced artifact matches its request).
• Git: audit an issue older than ~1 month before implementing it.
• .claude/rules.lock: the eight adopted rules with their wording hashes (rules_version = 1).

Test plan

• Each block appears verbatim in CLAUDE.md
• .claude/rules.lock parses as TOML (8 [rules.*] entries)

Closes #184