docs(m131): fleet console, memory, and run cost

[indykish]

Summary

• Delivers the Milestone 131 (M131) documentation to main.
• Documents fleet source editing, memory correction, bounded recent cost, lifetime spend, and stale-write protection.
• Preserves the Jul 17 and Jul 16 changelog entries in reverse-chronological order.

Root cause

Pull Request (PR) #141 targeted chore/m130-catalog-row-edit-changelog after that branch had already merged. This PR carries the two M131 documentation commits onto current main.

Verification

• make lint
• make test
• gitleaks detect --no-banner
• Final diff reviewed against origin/main: four intended documentation files, 36 insertions, 4 deletions.

Session notes

• Merged current origin/main into the published M131 branch without rewriting history.
• Resolved the sole conflict in changelog.mdx by preserving both entries.
• No OpenAPI, command-line interface, schema, version, or runtime changes.
• Pre-landing review found no unresolved issues.

Greptile Summary

This PR adds the M131 documentation updates for fleet operations and API behavior.

• Fleet detail docs now cover source editing, stale-write recovery, memory, run metrics, and recent cost bounds.
• Memory docs now describe dashboard/API inspection and fleet-write access for forgetting entries.
• The changelog adds the M131 release entry while preserving recent entries.
• The error-code reference now includes the fleet, catalog, and memory codes used by the new docs.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed docs.
• The error-code reference now matches the new changelog and memory API references.
• The memory access wording now separates inspection from forget permissions.

Important Files Changed

Filename	Overview
api-reference/error-codes.mdx	Adds canonical entries for the fleet stale-write, catalog stale-write, and missing memory error codes.
changelog.mdx	Adds the M131 release entry with fleet detail, memory forget, cost, and stale-write API notes.
fleets/library.mdx	Documents dashboard stale-edit protection for fleet library rows.
fleets/overview.mdx	Documents fleet detail source editing, stale-edit recovery, and bounded recent cost rollups.
memory.mdx	Clarifies memory inspection, fleet-write access for forgetting entries, and the DELETE behavior.

_{Reviews (2): Last reviewed commit: "docs: register fleet console error codes" | Re-trigger Greptile}

Context used (3)

• Knowledge Base — API reference
• Knowledge Base — Fleets
• Knowledge Base — Site infrastructure, validation, and contribution rules