docs: use bundled knowledge directions in README examples

[Mike-7777777]

What changes

The English and Chinese README direction examples now use agent_memory and llm_reasoning, both included in knowledge_base/. The instructions also explain that a custom knowledge file must exist before its name is added to the configuration.

Why

Copying the previous example into config/providers.local.json caused python run_pending_forge.py to reject both names before model execution. This was an incorrect documentation example. Runtime validation correctly rejects unknown directions and remains unchanged.

Validation

• Added two regression cases that extract the JSON examples from both READMEs, run direction selection, and verify the selected knowledge files exist. Both failed before the correction and pass afterward.
• Exercised the actual pending-Forge entrypoint with a temporary seed and configuration: the old example raises the reported ValueError; the corrected example reaches the Forge call with the intended directions. Model execution was intercepted at that boundary; no paid model request was made.
• The full offline Python suite, Ruff, compilation, model-reference checks, configuration projection, secret scan, release-tree check, and public-knowledge check pass locally.
• README freshness checks and Chinese prose checks pass. Code review found no actionable defects.

Scope check

• One issue and one independently reviewable change.
• No unrelated source changes, generated data, or credentials.
• Claims verified against executed tests and the runtime entrypoint.
• Checked open PRs before implementation; no overlapping PR was present.

Fixes #1