feat+docs(transpile-substrate): §1.6 three SDKs + emit_csharp/emit_python codegen

[AdaWorldAPI]

Answers the operator ask — "for Rust via lance-graph; for Python and C# we
need sort of an 'SDK' that does that for the others" — with both the doc and
its codegen implementation for two of the three languages.

Code — ogar-from-ruff::emit: two new emitters on the existing seam

emit_rust is the reference; this adds emit_csharp and emit_python
on the same &CompiledClass -> String seam (the codegen mode of the
per-language SDKs):

• emit_csharp → public sealed record AccountMove { public const uint ClassId = 0x00020202; public OgScalar name {get;init;} public ToOne<ResPartner> partner_id {…} public ToMany<AccountMoveLine> line_ids {…} }
• emit_python → @dataclass class AccountMove: CLASSID: ClassVar[int] = 0x00020202; name: OgScalar; partner_id: ToOne["ResPartner"]; line_ids: ToMany["AccountMoveLine"]

All three emitters use the same wrapper-contract type names (OgScalar /
ToOne / ToMany); only the bracket syntax differs (<T> Rust/C#, [T]
Python). A shared assoc_target() relation classifier drives all three — that
shared vocabulary is exactly what makes an SDK a mechanical transliteration
of one compiled spine, not a re-implementation. The classid travels with the
class; compute behaviour stays a trailing comment (the 15% adapter).
emit_rust's association loop was refactored onto the shared classifier (no
behavioural change).

Docs — new §1.6 "Three SDKs, one compiled spine (Rust · C# · Python)"

Every language SDK is three thin layers: (1) the address algebra
(FacetCascade + CascadeShape, byte-identical across languages), (2) a
ClassView reader over a pulled CompiledClass, (3) the per-language adapter
host for the 15% + the late classid → OGIT grounding resolve. Layer 1 is ~80
lines of core-only const fn, so an SDK transliterates rather than
re-implements. Two pull-back modes per host: codegen emit (this PR) and a thin
runtime reader over the rail artifact (never SurrealQL). Plus: §1.5 status
promoted (the arithmetic is now implemented as CascadeShape — lance-graph
#621); §6 "Built" lists the three emitters; §6.2 "Next" narrowed to the runtime
SDKs + wrapper-contract packages.

Test Plan

• 6 emit tests green (3 new: emits_csharp_record_with_wrapper_contract_types,
  emits_python_dataclass_with_wrapper_contract_types,
  all_three_emitters_share_the_same_type_vocabulary).
• clippy clean + rustfmt clean on emit.rs.
• Probe-workspace verified offline (the OGAR workspace's surrealdb-ast git dep
  is unresolvable offline; ruff_* patched to the local /home/user/ruff
  checkout, scoping resolution to ogar-from-ruff + ogar-vocab).

Companion to lance-graph #621 (facet::CascadeShape, the layer-1 algebra).

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