fix(plugins): rename ACONTEXT_USER_ID → ACONTEXT_USER_IDENTIFIER & remove unnecessary flush calls

[GenerQAQ]

Why we need this PR?

Two issues in the claude-code and openclaw plugins:

1. ACONTEXT_USER_ID is misleading — it's actually an identifier/tag for session scoping, not a login user ID. Priority was also inverted (auth.json winning over explicit env/config).
2. flush() is blocking and called in auto-learn paths unnecessarily. The server processes learning asynchronously via RabbitMQ workers, so flush is only needed for explicit user-triggered tools.

Describe your solution

Issue 1: Rename & fix priority

• Claude Code: New env var ACONTEXT_USER_IDENTIFIER (with ACONTEXT_USER_ID as legacy fallback). Priority: env var > auth.json > "claude_code".
• OpenClaw: New config key userIdentifier (with userId as legacy fallback). Priority: plugin config > auth.json > "openclaw".
• Default identifiers are now platform-specific (claude_code / openclaw) instead of generic "default".

Issue 2: Remove unnecessary flush calls

• Removed flush() from auto-learn (post-tool-use hook, agent_end), stop handler, and compaction/reset paths.
• Kept flush() only in explicit learn_now MCP tools where the user expects synchronous results.
• Renamed flushAndLearnIfActive → learnIfActive in openclaw.

Implementation Tasks

• Rename env var / config key with legacy fallback in both plugins
• Fix identifier resolution priority in both plugins
• Change default identifiers to platform-specific values
• Remove flush() from 4 automatic paths (2 in claude-code, 2 in openclaw)
• Update tests (3 new tests in claude-code, 2 updated in openclaw)
• Update docs (README, claude-code.mdx, openclaw.mdx, SKILL.md)
• Rebuild claude-code bundles

Impact Areas

• Documentation
• Other: Claude Code Plugin, OpenClaw Plugin

Checklist

• Open your pull request against the dev branch.
• All tests pass in available continuous integration systems (e.g., GitHub Actions).
• Tests are added or modified as needed to cover code changes.

[GenerQAQ]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

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