Network-config codegen

Codegen crate requirements for Network-config codegen (FEAT_0082) — translating the NetworkConfig IR into &'static bus tables and routing constants.

Feature: Network-config codegen FEAT_0082
status: open
satisfies: FEAT_0080
is satisfied by: REQ_0825, REQ_0826, REQ_0827, REQ_0828, REQ_0829

A codegen crate translating the NetworkConfig IR into a TokenStream of &'static bus tables and named routing constants, formatted with prettyplease for byte-stable, reviewable output.
Requirement: Emit static SubDeviceMap PDO tables REQ_0825
status: open
satisfies: FEAT_0082
is verified by: TEST_0834

Codegen shall emit a pub static PDO_MAP: &[SubDeviceMap] whose entries carry each device’s computed configured address, mapped RxPDO / TxPDO PdoEntry slices, and a derived expected_wkc (per Working-counter expectation... (REQ_0828)). The emitted types shall be the existing taktora_connector_ethercat types, named textually.
Requirement: Emit named routing and channel-name constants REQ_0826
status: open
satisfies: FEAT_0082
is verified by: TEST_0835

Codegen shall emit, per channel binding, a named EthercatRouting constant carrying the resolved subdevice address, direction, bit offset, and bit length, plus the channel-name string constant. The element type shall be a primitive (inline case) or an ESI-derived type.
Requirement: Configured addresses assigned by bus position REQ_0827
status: open
satisfies: FEAT_0082
is verified by: TEST_0836

Codegen shall assign each device’s configured station address as 0x1000 + n where n is its zero-based position in the bus-ordered device list, mirroring init_single_group. An explicit per-device address override shall take precedence when present and is reserved for bus segments the integrator does not control.
Requirement: Working-counter expectation derived, never overridden REQ_0828
status: open
satisfies: FEAT_0082
is verified by: TEST_0837

The expected_wkc for each SubDevice shall be derived solely from its mapped PDO directions (the canonical 0/1/2/3 rule). The toolchain shall provide no mechanism to override the derived value; there is exactly one source of truth.
Requirement: Generated output is byte-deterministic REQ_0829
status: open
satisfies: FEAT_0082
is verified by: TEST_0838

The same network.yaml plus the same pinned ESI inputs shall produce a byte-identical generated module across machines and toolchain versions. Timestamps, hash-map iteration order, and source ordering shall not leak into the output.