v2.0.0 — install integrity, fact fidelity, and a context reminder that measures

EPIC-008: the installer and detector stop producing signal they then measure.
Plugin+CLI dual registration is detected and no longer fakes a churn verdict;
detect writes the package manager it actually found (pnpm/yarn, through to
permissions.allow); CLAUDE_CONFIG_DIR and the allow list have one definition
each; rejected .mcp.json servers are honored; PreCompact is fail-safe with
collision-free state paths and 30-day retention; cli/ gains unit coverage;
docs and CLI UX close the gaps.

TASK-079: new context-size reminder (UserPromptSubmit). The model cannot see
its own context usage, so a hook reads the transcript tail, sums the tokens
actually re-sent, and once past a PO-frozen 120k injects one short note
suggesting /compact — once per crossing, re-armed only after a compaction.

BREAKING: `tune-context` with no subcommand no longer runs `init`; `init` is
now required explicitly. Also adds `tune-context --version`.

See CHANGELOG.md, including "Upgrading from 1.1.0".