Feature request: automatic session summarization + skill self-evolution (hermes-style loop)

Summary

Add the ability for sessions to be automatically summarized into reusable knowledge, and for skills to self-evolve — a periodic self-review/summary loop that writes distilled learnings back into the knowledge system (similar to hermes-style agents).

Motivation

• Long conversations accumulate reusable learnings that are lost when context gets compacted.
• Skills stay static unless manually edited; they could absorb distilled lessons automatically (self-improvement).

Proposed behavior

1. After N turns (or via an explicit command such as opencode summarize), produce a concise, citable summary of the session's reusable knowledge.
2. Optionally write that distilled knowledge into an auto-managed knowledge folder (indexed by a local search engine) so future sessions can retrieve it.
3. Skills/agents can optionally self-evolve: when a clear recurring pattern is detected, append the experience back into the skill's own definition.
4. Rate-limited + opt-in/opt-out (off by default or per-skill toggle) to avoid noise.

Acceptance criteria

• A trigger (command or prompt) that summarizes the current session into a knowledge file.
• The summary is retrievable later (indexed, with source references).
• Optional self-evolution hook for skills, gated behind a flag.

Additional context

Adaptable to existing skill-loading/knowledge conventions in opencode. Happy to iterate on the design in the issue thread.

Start by tracing the existing skill-loading and knowledge conventions, then locate the command entry point for a possible opencode summarize trigger. Review how the local search index and source references are handled before defining the opt-in, rate-limited session-summary flow and the gated self-evolution hook. Done means summaries are written to retrievable knowledge files and the optional skill update path is covered by the acceptance criteria.