Use UUIDs for messages instead of IDs

[norkans7]

Addresses #27

[Copilot]

Pull Request Overview

This PR migrates message identification from integer IDs to UUIDs throughout the codebase. The change affects message structures, database queries, API endpoints, and test fixtures to use UUID-based identifiers instead of numeric IDs.

• Replaces MsgID (int64) with MsgUUID (string UUID) across all message-related types
• Updates API contracts to use uuid field instead of id for messages
• Modifies database queries to return/query by UUID instead of ID

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
core/models/msg.go	Defines new MsgUUID type and updates message structs to use UUID instead of ID
core/models/msg_test.go	Updates test assertions to check UUIDs instead of IDs
core/queue/outboxes.go	Changes item ID generation to use UUID format
core/queue/outboxes_test.go	Updates test data and assertions to use UUIDs
core/courier/courier.go	Updates courier interface to accept MsgUUID instead of MsgID
core/courier/courier_test.go	Updates test expectations for UUID-based courier calls
core/courier/events.go	Changes courier events to use MsgUUID
service.go	Updates message delivery confirmation to parse and validate UUIDs
web/client.go	Changes acknowledgment item ID format to use UUID
web/commands/ack_chat.go	Updates acknowledgment command to use MsgUUID
web/server.go	Updates send endpoint to accept UUID instead of ID
web/server_test.go	Adds UUID generator seeding and updates test fixtures
testsuite/courier.go	Updates mock courier to work with UUIDs
testsuite/testdata.go	Changes helper functions to return MsgUUID instead of MsgID

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[Copilot]

The validation tag should be required,uuid to match standard validator library conventions where required comes before format validators.

Suggested change

	UUID models.MsgUUID `json:"uuid" validate:"uuid,required"`
	UUID models.MsgUUID `json:"uuid" validate:"required,uuid"`

[Copilot]

The error message wrapping is redundant. Either return errors.New(\"invalid uuid\") directly or use a more descriptive message like fmt.Errorf(\"invalid msg uuid: %s\", msgUUID) without wrapping.

Suggested change

	return fmt.Errorf("error parsing msg uuid: %w", errors.New("invalid uuid"))
	return fmt.Errorf("invalid msg uuid: %s", msgUUID)