feat: integrate 5 feature branches, upstream fixes, and MIME detection fix

Squashed 5 commits:

Features (from 5 feature branches):
- MCP fix, pipe mute, stub recovery
- KAIROS activation, openclaw autonomy
- Daemon/job command hierarchy + cross-platform bg engine

Upstream fixes:
- fix: Bun.hash compatibility
- chore: chrome dependency update
- docs: browser support guide

MIME detection fix:
- Screenshot detectMimeFromBase64(): decode raw bytes from base64
  instead of broken charCodeAt comparison
- Fixes API 400 on Windows (JPEG) and macOS (PNG) screenshots

docs/test-plans/openclaw-autonomy-baseline.md

@@ -0,0 +1,88 @@
+# OpenClaw Autonomy Baseline Test Spec
+
+## Purpose
+
+This test spec locks the current behavior of the existing trigger and context layers before any formal autonomy-subsystem implementation begins.
+
+At this stage, production code is read-only. Only test files, fixtures, and planning documents may change.
+
+## Goal
+
+Establish a stable baseline around the parts of `Claude-code-bast` that later autonomy work is most likely to touch:
+
+- proactive state handling
+- cron task storage semantics
+- cron scheduler helper semantics
+- user-context cache and `CLAUDE.md` injection behavior
+
+## Out of Scope for This Baseline Round
+
+- New authority behavior (`AGENTS.md` / `HEARTBEAT.md`)
+- New detached-run ledger behavior
+- New flow behavior
+- UI redesign
+
+## Files Under Baseline Protection
+
+- `src/proactive/index.ts`
+- `src/utils/cronTasks.ts`
+- `src/utils/cronScheduler.ts`
+- `src/context.ts`
+
+## Test Files Added In This Round
+
+- `src/proactive/__tests__/state.baseline.test.ts`
+- `src/commands/__tests__/proactive.baseline.test.ts`
+- `src/utils/__tests__/cronTasks.baseline.test.ts`
+- `src/utils/__tests__/cronScheduler.baseline.test.ts`
+- `src/__tests__/context.baseline.test.ts`
+
+## Baseline Assertions
+
+### Proactive state
+
+1. Activating proactive mode sets active state and activation source.
+2. Pausing proactive mode suppresses `shouldTick()` and clears `nextTickAt`.
+3. Blocking context suppresses `shouldTick()` and clears `nextTickAt`.
+4. Subscribers are notified on state transitions.
+5. The `/proactive` command enables proactive mode and emits the expected hidden reminder.
+6. The `/proactive` command disables proactive mode on the second invocation.
+
+### Cron task storage
+
+1. Session-only cron tasks remain in memory only.
+2. Durable cron tasks are persisted to `.claude/scheduled_tasks.json`.
+3. Daemon-style `dir`-scoped reads exclude session-only cron tasks.
+4. `removeCronTasks()` without `dir` can remove session-only tasks.
+5. `removeCronTasks()` with `dir` does not mutate session-only task storage.
+
+### Cron scheduler helpers
+
+1. `isRecurringTaskAged()` preserves current aging semantics.
+2. `buildMissedTaskNotification()` preserves the current AskUserQuestion safety wording.
+3. `buildMissedTaskNotification()` preserves code-fence hardening for prompt bodies that contain backticks.
+
+### User context caching
+
+1. `getUserContext()` includes `currentDate`.
+2. `getUserContext()` includes mocked `claudeMd` content when memory loading is enabled.
+3. `CLAUDE_CODE_DISABLE_CLAUDE_MDS` suppresses `claudeMd`.
+4. `setSystemPromptInjection()` clears the memoized user-context cache.
+5. `getSystemContext()` reflects the injection after cache invalidation.
+
+## Remaining Baseline Gaps
+
+The following areas are intentionally deferred because they require higher-cost harnessing and should still avoid production-code changes:
+
+1. `useScheduledTasks.ts` hook-level runtime behavior
+2. `src/cli/print.ts` full headless scheduler loop behavior
+3. `useProactive.ts` hook timer behavior
+4. end-to-end queue interaction between proactive ticks and `SleepTool`
+
+## Acceptance
+
+This baseline round is complete when:
+
+1. The four new test files pass.
+2. No production source files are modified.
+3. The tests are stable enough to serve as a pre-implementation guardrail.