fix(core): read AgentRun ledgers written by any version

[Astro-Han]

Summary

AGENT_RUN_EVENT_TYPES served two roles at once: the set of event types this build writes, and the set a reader accepts. The AgentRun ledger is append-only and outlives the build that wrote it, so those cannot be the same set. #1755 retired the usage_recorded writer and deleted its entry in one commit; the next build then could not decode records the previous one had already persisted, and the desktop app failed to start (#1942).

Only the write side can be a closed set:

• Reads take type as an open string. The envelope around it is still validated exactly, so a damaged record is still rejected — tolerating an unknown type is not tolerating an unreadable one.
• Appends take EmittedAgentRunEvent, so a misspelled or retired type fails to compile at the call that would persist it.

That is what makes retiring a writer safe, and it is why usage_recorded is gone again. #1945 stopped the crash the only way the old shape allowed: by putting a type nothing writes back into the catalogue this build writes from. With the two contracts separated, the tombstone is unnecessary and the entry can be removed for real.

A conversation copy now drops an event this build does not emit rather than carrying its unrewritten source-owned ids into the target — the rewriters cannot inspect a payload they do not know.

Closes#1942.

Verification

• npm run lint, npm run format:check, full npm run build — clean.
• @maka/core 753/753, @maka/headless 1314/1314 pass.
• @maka/storage and @maka/runtime: the 7 storage (schema migration/backup) and 4 runtime (macOS /var → /private/var realpath) failures reproduce identically on main — verified by running the same suites in a clean main checkout, where storage in fact fails 9.

Mutation-tested every new assertion, each confirmed to go red:

Mutation	Result
Restore the closed-set check in decodeAgentRunEvent (i.e. reintroduce #1942)	core contract + storage cross-version read fail
Widen appendEvent back to AgentRunEvent	TS2578: Unused '@ts-expect-error' directive — build fails
Remove the blank-type guard	core envelope-rejection test fails
Remove the unknown-type filter in conversation-copy	copy test fails

Root cause

A write-side catalogue was used as a read-side contract. Backward compatibility can be enforced by discipline at the writer; forward compatibility cannot, because the writing version does not exist yet when the reader ships. The reader must therefore be tolerant of type by construction, which is the only part of the record whose value space legitimately grows across versions.

Review focus

harbor-cell.ts constructs two records (trace_write_failed, event_corrupt) that are persisted to a benchmark artifact; both now carry the write contract, so a typo there is a compile error rather than a downstream "corrupt artifact" diagnostic that points at the wrong cause.