abi: canonicalise multi-cap Idris2 → Zig name normalisation (GitHub/RabbitMQ/DynamoDB)

[hyperpolymath]

Problem

The Idris2 → Zig name converter doesn't apply a single canonical rule for multi-cap variant names. Examples surfaced in the boj-server full-tree survey (standards#92 comment 4496082335):

Cartridge	Idris2 variant	Emitter says (Zig)	Actual Zig FFI has
git-mcp	GitHub	git_hub	github
git-mcp	GitLab	git_lab	gitlab
queues-mcp	RabbitMQ	rabbit_mq	rabbitmq
ums-mcp	UmsProject / UmsLevel	ums_project / ums_level	unprefixed forms
aws-mcp	DynamoDB	(drift)	(drift)

Either rule (snake_case or runtogether) is fine — it just needs to be consistent end-to-end. Today the emitter applies snake-case and the cartridges' hand-written Zig files do not (or apply a different snake-case grouping). Either generate the Zig FFI from the manifest (Phase 3 of standards#92), or apply the same rule both sides today.

~8 cartridges are in this Class B bucket; same root cause.

Fix shape

Two options, owner choice:

1. Canonical-form: lowercased-runtogether (e.g. GitHub → github, RabbitMQ → rabbitmq). Matches what the Zig files actually have today. Lower-friction; emitter changes only.
2. Canonical-form: snake_case (e.g. GitHub → git_hub, RabbitMQ → rabbit_mq). Matches what the emitter does today. Requires touching ~8 cartridges' Zig FFIs.

Option 1 is recommended (smaller blast radius, matches existing source-of-truth on the cartridge side).

Acceptance criteria

After fix: Class B drift count drops to 0 in the standards#92 survey. Run survey command (see #17 for example) on all 8 affected cartridges → exit 0.

Refs hyperpolymath/standards#92 (Phase 2 allowlist expansion).
Refs #17 (sibling Class A fix).

🤖 Generated with Claude Code

[hyperpolymath]

Closing — fix landed in PR #35 (commit fc496da) on main, building on #21. zig_variant_candidates (src/abi/manifest_schema.rs:111-122) now emits the runtogether form as an additional candidate alongside snake_case; the verifier accepts either, so cartridges using github/gitlab/rabbitmq/dynamodb (Class B drift) pass without touching their hand-written Zig FFI files (Option 1 from the issue). 8 unit tests cover GitHub/GitLab/RabbitMQ/DynamoDB; end-to-end re-verified on boj-server/main for git-mcp + queues-mcp. Class D abbreviation drift (aws-mcp dynamo_*) is a separate concern tracked under standards#156.