feat(#401): add public model types for ModemManager domain

[cachebag]

This PR Defines the initial public surface for the mmrs crate: Modem, ModemState, and AccessTechnology for modem-level state; Sim and SimLockState for SIM slots; Bearer, BearerConfig, BearerStats, Ip4Config, and IpType for packet-data bearers; and ModemError plus a Result alias for fallible operations.

Constants and predicates (from_raw, has_lte, is_3gpp, requires_pin, etc.) decode ModemManager's MM_MODEM_STATE_*, MM_MODEM_ACCESS_TECHNOLOGY_*, MM_MODEM_LOCK_*, and MM_BEARER_IP_FAMILY_* constants so callers never touch raw integers. Types live under mmrs::api::models and are re-exported at the crate root and via pub mod models.

[Copilot]

Pull request overview

Introduces the initial public “model types” layer for the mmrs crate, providing typed representations of ModemManager concepts (modems, SIMs, bearers) plus a crate error type and Result alias so callers can avoid working with raw integer constants.

Changes:

• Adds public model types under mmrs::api::models, re-exported via mmrs::models and at the crate root.
• Implements decoding helpers/predicates for ModemManager state/bitmask/lock constants (from_raw, has_lte, is_3gpp, requires_pin, etc.).
• Adds ModemError and a Result<T> alias; updates crate docs and changelog; adds thiserror dependency.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
mmrs/src/lib.rs	Adds crate-level docs and re-exports for the new public model surface (mmrs::models and root re-exports).
mmrs/src/api/mod.rs	Documents the api module and exposes api::models.
mmrs/src/api/models/mod.rs	Defines the models module structure and re-exports all model types.
mmrs/src/api/models/modem.rs	Adds ModemState, AccessTechnology, and Modem snapshot types with decoding/predicates/tests.
mmrs/src/api/models/sim.rs	Adds Sim and SimLockState with decoding/predicates/tests.
mmrs/src/api/models/bearer.rs	Adds bearer-related types (Bearer, BearerConfig, BearerStats, Ip4Config, IpType) with tests.
mmrs/src/api/models/error.rs	Adds ModemError and Result alias with tests.
mmrs/CHANGELOG.md	Documents the newly added public model types.
mmrs/Cargo.toml	Adds thiserror workspace dependency for error derivations.

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