STABILITY: promote 13 packages experimental → mostly stable

[pequalsnp]

Summary

• Walked the STABILITY.md package matrix against the v1-prep CHANGELOG entries (which closed a string of explicit STABILITY rows) plus the integration / e2e test coverage that landed alongside them.
• Promotes 13 packages whose feature surface is now tested end-to-end and whose notes column carries no open sharp edge.
• Documents the holdouts explicitly so the next promotion pass has a checklist instead of a hunt.

Promoted

Layer	Packages
State	pkg/state/dynamodb, pkg/state/valkey
Streaming runtime	pkg/exec/streaming, pkg/exec/bootstrap, pkg/exec/replay
Snapshot sources	pkg/source/snapshot/jsonl, pkg/source/snapshot/s3
Replay	pkg/replay/s3
Query	pkg/query/grpc, pkg/query/typed
Admin	pkg/admin
Algebra	pkg/monoid/compose
Tools	cmd/murmur-codegen-typed

Held back on purpose

• pkg/source/kafka — per-partition concurrency is fresh, needs soak.
• pkg/exec/processor + pkg/exec/lambda/{kinesis,dynamodbstreams,sqs} — processor's docstring ties its stability to the Lambda runtimes, which haven't been exercised against real (non-local) AWS yet. Promote the four together post real-AWS soak.
• pkg/source/snapshot/mongo, pkg/source/snapshot/dynamodb — open sharp edges still documented.
• pkg/monoid/sketch/{hll,topk,bloom} — cross-runtime encoding portability not yet proven.
• pkg/projection, pkg/observability/autoscale — too new.
• pkg/pipeline, pkg/murmur — author-flagged "expect renames before v1."
• pkg/exec/batch/sparkconnect — replace-directive gotcha.
• cmd/murmur-ui — explicitly demo-grade.

Test plan

• Skim the new CHANGELOG entry — does the holdout-rationale read accurately?
• Skim each promoted row in STABILITY.md — confirm the notes column is still accurate for a "mostly stable" reader.
• CI green (this is docs-only — golangci-lint / unit / integration shouldn't care).

🤖 Generated with Claude Code