Persist Matrix key requests safely and pin the local master

[TroyHernandez]

Keep decrypted Matrix sync batches intact when room-key request transport fails. The adapter now persists the mutated crypto state before sending any request, retries unsent requests with the same id, and treats cancellation or sent-marker persistence failures as warnings. This prevents a network failure from replaying the sync against already-advanced Olm ratchets.

Same-user forwarded-key recovery now queries devices with the master public key loaded from the local cross-signing store. Missing or unreadable local keys leave this user's devices untrusted for recovery. Reading the pin when querying also picks up bootstrap performed after the crypto context was initialized.

Required optional dependency increases: mx.client >= 0.2.0.8 and mx.crypto >= 0.2.1.1. The new request-state and cross-signing APIs require these floors.

This branch starts from current main (0.0.1.24), includes its newer thread/media behavior, and excludes the separate Slack lifecycle branch and NAMESPACE registrations. Version 0.0.1.25 is recorded in its own Bump version to 0.0.1.25 commit touching only DESCRIPTION and NEWS.md. CI configuration is a separate commit.

Validation: all four final sources, including mx.crypto, were installed into a fresh isolated library. Full suites pass: chat.api 1092/1092, mx.client 315/315, mx.crypto 100/100, mx.api 208/208. Changed CI YAML and shell syntax pass local validation. Regression tests cover save/send/retry ordering and missing/corrupt/local-master behavior.

Landing prerequisites:

• Add cross-signing signer and forwarded Megolm primitives mx.crypto#7 and Add Matrix cross-signing upload endpoints mx.api#20 merge first.
• mx.crypto 0.2.1.1 and mx.api 0.3.0.2 must then be published to the cornball-ai drat repository with separate maintainer authorization.
• Add pinned cross-signing and durable room-key recovery mx.client#26 must merge to main before this PR's CI can resolve the required mx.client version.

Expected temporary CI failures: the existing Matrix setup clones mx.api and mx.client from their GitHub default branches and enforces the mx.client floor. Linux also needs the new mx.crypto release from drat. The new crypto install explicitly bypasses rapt's older binary and checks the floor; macOS retains its existing optional-crypto split. Rerun CI after the upstream publication and mx.client merge. No package publication, bot deployment, or console/SAS verification is included here.