chore(release): 2.0.0 — three-plugin split

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project are documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [2.0.0] - 2026-07-22
+
+### BREAKING
+
+- The monolithic `session-optimizer` plugin is split into three
+  independently installable plugins, shipped from the same marketplace:
+  - **context-guard** — `Stop`-hook context budget with a per-model
+    checkpoint protocol, budgeted `memory-writer` checkpoint subagent, and
+    a `SubagentStop` spend tracker.
+  - **refine-gate** — `UserPromptSubmit` prompt-binding gate + `/refine`
+    skill.
+  - **statusline** — multi-line status bar with RGB-gradient context bars,
+    cost tracking, telemetry, and rate-limit gauges.
+- The root `session-optimizer` plugin remains **only as a deprecation
+  shim**: it registers no functional hooks and just announces the
+  migration at session start.
+
+### Added
+
+- Runtime Cortex detection: the checkpoint protocol uses a generic,
+  vanilla-Claude-Code wording by default and switches to the scoped memory
+  layer only when it is detected as installed.
+- Statusline install skill (`/plugin install statusline@...`, then ask
+  Claude to "install the statusline") plus an auto-update hook that keeps
+  the installed copy in sync with the plugin's bundled assets.
+- CI (`.github/workflows/ci.yml`): runs all three test suites, shellchecks
+  the statusline renderer, and validates every plugin/hook/marketplace
+  JSON.
+- Privacy policy (`PRIVACY.md`), as required by the plugin Directory
+  Policy.
+
+### Changed
+
+- Hook registration is single-sourced in each plugin's `hooks/hooks.json`
+  (no duplicate definitions in `plugin.json`).
+- Statusline documentation translated to English.
+- Statusline renderer is shellcheck-clean at full severity; remaining
+  suppressions are justified inline.
+
+### Migration from 1.x
+
+1. Install the plugins you actually use (any subset): `context-guard`,
+   `refine-gate`, `statusline`.
+2. Uninstall the old plugin: `/plugin uninstall session-optimizer`.
+3. Your `~/.claude/ctxguard-thresholds.json`, checkpoint files, and
+   statusline config are untouched — the new plugins read the same paths.
+4. If you had installed the `memory-writer` agent manually into
+   `~/.claude/agents/`, you can remove it; context-guard ships its own
+   copy (`context-guard:memory-writer`).
+
+## [1.4.3] and earlier
+
+Releases up to `v1.4.3` shipped the monolithic `session-optimizer` plugin.
+See the git tags (`v1.0.0` … `v1.4.3`) for their history.