chore(Cargo): bump rust-nostr to version 0.44

[jgmontoya]

This PR upgrades the workspace dependency nostr from 0.43 to 0.44 and updates timestamp usage across the codebase to the new Timestamp API, replacing deprecated Timestamp::as_u64() calls with Timestamp::as_secs() to use seconds-based representations. The change is an internal refactor of timestamp handling and storage serialization with no changes to public APIs or behavioral logic beyond timestamp units.

What changed:

• Bumped nostr dependency in workspace Cargo.toml from "0.43" to "0.44".
• mdk-core: Replaced Timestamp::as_u64() usages with as_secs() in message validation, timestamp comparisons, epoch snapshot code, error messages, and related tests.
• mdk-sqlite-storage: Switched timestamp serialization for groups, messages, processed messages, and welcomes to as_secs() when persisting timestamps to the database.
• mdk-uniffi: Updated FFI-facing conversions (Group and Message timestamp fields) to expose seconds via as_secs().
• mdk-memory-storage: Adjusted internal timestamp handling to use as_secs() where applicable.
• CHANGELOGs: Added entries documenting the nostr upgrade and the migration from as_u64() to as_secs().

Security impact:

• No cryptographic, key handling, SQLCipher configuration, credential, or identity-binding changes were made; this PR only changes timestamp representations (no security-sensitive code modifications).

Protocol changes:

• No changes to MLS implementation or MIPs; Nostr integration change limited to dependency upgrade and adapting to the nostr Timestamp API (use of seconds rather than deprecated method).

API surface:

• No breaking changes to public function signatures, types, traits, or FFI boundaries were introduced; timestamp representation changes are internal and the UniFFI layer still exposes numeric timestamp fields (now in seconds).
• Storage schema remains the same (same columns), but persisted timestamp values are now written as seconds.

Testing:

• Tests and test helpers in mdk-core and related crates were updated to assert seconds-based timestamps (replacing prior as_u64-based expectations).

[coderabbitai]

📝 Walkthrough

Walkthrough

Replaced uses of Timestamp::as_u64() with Timestamp::as_secs() across core, storage, conversion, and tests, and bumped the workspace nostr dependency from 0.43 to 0.44.

Changes

Cohort / File(s)	Summary
Dependency Cargo.toml	Bumped nostr workspace dependency from 0.43 to 0.44.
Core logic & tests crates/mdk-core/src/messages.rs, crates/mdk-core/src/test_util.rs	Replaced as_u64() with as_secs() in timestamp validation, epoch/commit handling, and test helpers; updated assertions and error messages to seconds.
Storage layer crates/mdk-sqlite-storage/src/... \crates/mdk-sqlite-storage/src/groups.rs`, `crates/mdk-sqlite-storage/src/messages.rs`, `crates/mdk-sqlite-storage/src/welcomes.rs``	Serialized timestamps (last_message_at, created_at, processed_at) using as_secs() instead of as_u64() in DB INSERT/UPDATE paths.
Public conversions crates/mdk-uniffi/src/lib.rs	Conversions for public Group and Message types now use as_secs() for last_message_at / processed_at.
Changelogs crates/mdk-core/CHANGELOG.md, crates/mdk-sqlite-storage/CHANGELOG.md, crates/mdk-uniffi/CHANGELOG.md	Added Unreleased entries documenting the nostr upgrade and replacement of as_u64() with as_secs().

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Suggested labels

storage

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title accurately describes the main change: upgrading the rust-nostr dependency from version 0.43 to 0.44, which is reflected throughout the changeset in Cargo.toml, timestamp handling updates, and changelog entries.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
No Sensitive Identifier Leakage	✅ Passed	PR exclusively modifies timestamp handling via as_u64() to as_secs() conversion and nostr dependency bump; no error messages, logging, or Debug implementations expose sensitive identifiers.

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✨ Finishing touches

• 📝 Generate docstrings

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[github-actions]

✅ Coverage: 88.74% → 90.71% (+1.97%)

[github-actions]

✅ Coverage: 88.74% → 90.71% (+1.97%)

[coderabbitai]

Actionable comments posted: 3

🤖 Fix all issues with AI agents

In `@crates/mdk-core/CHANGELOG.md`:
- Line 28: The CHANGELOG entry about upgrading the `nostr` dependency needs a PR
link appended; update the entry string ("Upgraded `nostr` dependency from 0.43
to 0.44, replacing deprecated `Timestamp::as_u64()` calls with
`Timestamp::as_secs()`") to include the PR reference in the required format
`([`#123`](https://github.com/marmot-protocol/mdk/pull/123))`, replacing 123 with
the actual PR number.

In `@crates/mdk-sqlite-storage/CHANGELOG.md`:
- Line 32: The changelog entry about upgrading the nostr dependency is missing
the required PR link; update the line mentioning "Upgraded `nostr` dependency
from 0.43 to 0.44, replacing deprecated `Timestamp::as_u64()` calls with
`Timestamp::as_secs()`" to append the PR reference in the standard format (e.g.,
add " (PR #<number>)" or the full PR URL) at the end of that entry so it
complies with CHANGELOG guidelines.

In `@crates/mdk-uniffi/CHANGELOG.md`:
- Line 34: The changelog entry mentioning the nostr dependency upgrade and
replacement of Timestamp::as_u64() with Timestamp::as_secs() is missing the
required PR link; update the entry in CHANGELOG.md (the line referencing "nostr"
and the method names Timestamp::as_u64() -> Timestamp::as_secs()) by appending
the corresponding PR URL (e.g., " (`#1234`)" or full link) to the end of the
sentence so it complies with the project's changelog guidelines.

[github-actions]

✅ Coverage: 88.74% → 90.71% (+1.97%)

[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

crates/mdk-uniffi/CHANGELOG.md (1)

32-41: Remove the duplicate empty ### Changed section.

Two ### Changed headings under ## Unreleased creates ambiguity and breaks the changelog structure. Keep a single ### Changed section. As per coding guidelines, Keep a Changelog structure should be consistent.

🧹 Proposed fix

@@
 ### Changed
 
 - Upgraded `nostr` dependency from 0.43 to 0.44, replacing deprecated `Timestamp::as_u64()` calls with `Timestamp::as_secs()` ([`#162`](https://github.com/marmot-protocol/mdk/pull/162))
 - Changed `get_messages()` to accept optional `limit` and `offset` parameters for pagination control. Existing calls must be updated to pass `None, None` for default behavior (limit: 1000, offset: 0), or specify values for custom pagination. ([`#111`](https://github.com/marmot-protocol/mdk/pull/111))
 - Changed `get_pending_welcomes()` to accept optional `limit` and `offset` parameters for pagination control. Existing calls must be updated to pass `None, None` for default behavior (limit: 1000, offset: 0), or specify values for custom pagination. ([`#119`](https://github.com/marmot-protocol/mdk/pull/119))
 - Changed `new_mdk()`, `new_mdk_with_key()`, and `new_mdk_unencrypted()` to accept an optional `MdkConfig` parameter for customizing MDK behavior. Existing calls must be updated to pass `None` for default behavior. ([`#155`](https://github.com/marmot-protocol/mdk/pull/155))
-
-### Changed

[github-actions]

✅ Coverage: 88.74% → 90.71% (+1.97%)