chore(linkedin-studio): release v0.5.2 — SB-S2 evolution loop

Bump version declarations 0.5.1 → 0.5.2 (plugin.json SSOT + README badge +
CLAUDE.md header + CHANGELOG [0.5.2]) for SB-S2. Flip the architecture SB-S2 row
to landed (+ top status: S0+S1+S2 landed, 82 tests). Additive minor: count-neutral
(no command/agent/ref/skill); voice-trainer unchanged. Gate 93/0/0, hook suite
136/0. Polyrepo release (tag v0.5.2 + catalog ref) follows (operator push-OK for today).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RigJBiRFNtFZKCz21qNbQ4

CHANGELOG.md

@@ -5,6 +5,18 @@ All notable changes to this project will be 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).
 
+## [0.5.2] - 2026-06-23
+
+### Added — SB-S2: the evolution loop (second-brain arc)
+
+**The compounding mechanism.** An operator-invoked, operator-gated consolidation pass that reads the published gold signal + tributary deltas and proposes a **diff** to the two-layer `brain/profile.md` — never a silent overwrite. **Non-breaking** (additive minor): count-neutral (no command/agent/reference/skill); `voice-trainer` unchanged; one session-start hook edit (zero-dep).
+
+- **Deterministic engine** (`scripts/brain/src/consolidate.ts`): `proposeDiff`/`applyDiff` (pure) — add / reject-`ai-draft` (model-collapse guard, in code) / evidence-bump / promote at N=3 / conflict→keep-both with **distinct ids** (primary `mintEntityId`, alt `mintContentId` — no duplicate-id corruption; no supersede, that's S3) / decay-flag at 90d (dynamic only; static decay-exempt). `applyDiff` round-trips through the SB-S0 grammar; re-running is idempotent.
+- **`brain consolidate` CLI**: `--gather` (reads published bodies since last run + the profile, for the invoking session to extract candidates — no new agent), `--propose --candidates <json>` (validates shape + single-line; writes `brain/pending-diff.{md,json}`; never touches profile.md), `--apply --diff <json> --confirm` (the ONLY path that writes profile.md; refuses without `--confirm`; records `brain/consolidation-state.json`).
+- **Session-start** (`hooks/scripts/session-start.mjs`, zero-dep edit): unconditional scaffold-ensure (fresh-install path) + a consolidation-due nudge (counts published records + reads the sidecar `last_run` via `getDataRoot`; no `profile.md` parse) + a brain-init nudge.
+- **Operator scope:** journal-capture deferred · the invoking session does the fuzzy extraction (no new agent) · motor-only (no `profile.md` reader until SB-S3). Docs: `docs/second-brain/consolidation-loop.md`.
+- **Tests.** brain suite 63 → 82 (`consolidate` 12 + `consolidate-cli` 7); hook suite 131 → 136 (new `session-start-brain-consolidation` 5); gate `scripts/test-runner.sh` 93/0/0 (`BRAIN_TESTS_FLOOR` 63→82; assertion floor unchanged at 78 — no new gate section). Light-Voyage-hardened (brief-reviewer REVISE, plan-critic REPLAN, scope-guardian ALIGNED — all folded).
+
 ## [0.5.1] - 2026-06-23
 
 ### Added — SB-S1: ingest + the published gold signal (second-brain arc)