Use the shared protocol

[kerthcet]

What this PR does / why we need it

Which issue(s) this PR fixes

Fixes #6

Special notes for your reviewer

Does this PR introduce a user-facing change?

[Copilot]

Pull request overview

This PR centralizes the daemon↔server wire format into a new shared Rust crate (sandd-protocol) and updates both server and sandd to import protocol types from that crate instead of maintaining duplicated/embedded protocol definitions.

Changes:

• Added new workspace member crate protocol (sandd-protocol) containing the shared Message, DaemonMetadata, and SnapshotInfo types.
• Updated server and sandd crates to depend on and use sandd_protocol::* imports; removed the old sandd local protocol module.
• Strengthened snapshot-related message payloads to use typed SnapshotInfo instead of untyped serde_json::Value.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
server/src/server.rs	Switch protocol Message import to sandd_protocol.
server/src/registry.rs	Switch protocol imports to sandd_protocol.
server/src/lib.rs	Remove local protocol module usage and import shared Message.
server/Cargo.toml	Add path dependency on sandd-protocol.
sandd/src/snapshot/types.rs	Re-export SnapshotInfo from shared protocol; remove local definition.
sandd/src/session.rs	Switch protocol Message import to sandd_protocol.
sandd/src/protocol.rs	Delete duplicated protocol definitions from daemon crate.
sandd/src/main.rs	Remove local protocol module usage; switch imports/types to sandd_protocol.
sandd/Cargo.toml	Add path dependency on sandd-protocol.
protocol/src/lib.rs	Introduce shared protocol definitions; type snapshot payloads as SnapshotInfo.
protocol/Cargo.toml	Define new sandd-protocol crate and its dependencies.
Cargo.toml	Add protocol to workspace members.
Cargo.lock	Record new workspace package sandd-protocol in the lockfile.

Comments suppressed due to low confidence (1)

protocol/src/lib.rs:9

• created_at is documented as milliseconds, but snapshot creation currently uses SystemTime::now().duration_since(UNIX_EPOCH).as_secs() (seconds) in sandd/src/snapshot/manager.rs. This makes the shared protocol ambiguous and will cause consumers to misinterpret timestamps if they follow the protocol docs. Either keep seconds (update docs/comments here and in protocol::SnapshotInfo) or switch the producer to milliseconds and migrate/handle existing on-disk snapshot JSON.

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[kerthcet]

/lgtm
/kind feature

[kerthcet]

/lgtm

[InftyAI-Agent]

Approved: PR has both lgtm and approved labels