[feature]: Memory files grow unbounded on disk

[faisalishfaq2005]

What problem would this solve?

src/core/memory.ts only reads the last MAX_MEMORY_CHARS (12k) of a memory file into prompts, but appendRunRecord appends forever, so the file grows without bound on disk even though only the tail is ever used.

Proposed solution

Add a way to trim old run records while keeping the file human-readable and diffable , either a loopflow memory --prune command or automatic rotation that keeps the N most recent records. Pure-function trimming logic should stay testable.

Alternatives considered

No response

Scope

• I've checked this isn't already on the roadmap in the README.
• This can't reasonably be expressed as a loop instead of engine code.