Reconcile version identity and make the untagged state honest

[aaylward]

Closes #44 (top-tier from the whole-project review). The product version disagreed three ways — smithy::Version() said 0.1.0, the client User-Agent said 0.0.0-dev, MODULE.bazel said 0.0.0 — and the CHANGELOG / versioning docs advertised a v0.1.0 tag and release that don't exist. Per the decision to stay untagged, this reconciles the identity and makes the docs honest rather than cutting a release.

Changes

• One product version, consistently pre-release. smithy::Version() (runtime/src/core/version.cc, the single source of truth) and ClientConfig::user_agent both report 0.1.0-dev. A consumer now sees one coherent, honestly-unreleased version.
• bzlmod module version stays 0.0.0 in MODULE.bazel — the established unpublished-module convention, which git_override/local_path_override ignore anyway — now with a comment explaining it is a distinct identifier from the product version (not an accidental mismatch). This is why the quickstart's bazel_dep(version = "0.0.0") stays valid and unchanged.
• CHANGELOG [0.1.0] - 2026-07-07 → [Unreleased]; the broken releases/tag/v0.1.0 link now points at the commit history; the intro states the work is developed on main and not yet tagged.
• versioning.md gains a "Current state: pre-release, untagged" section explaining the two version identifiers and how to pin a commit (there's no tag to pin), and what to change when 0.1.0 is actually cut.
• quickstart.md: the unfillable commit = "<pin a commit>" becomes a real 40-char SHA placeholder with a pointer to copy one from commits/main, and notes the version is ignored under an override.
• README heading: "What works today (v0.1.0)" → "(0.1.0-dev, untagged)".

No git tag is cut.

Testing

• version_test updated and passing on 0.1.0-dev; bazel test //runtime/... //examples/... (minus Beast targets per docs): 38/38 pass.
• Rebuilt the out-of-tree examples/bazel-consumer module against the edited MODULE.bazel — configures and builds cleanly (the module-version comment is inert; the consumer overrides the source).
• Docs/markdown otherwise; no generated-code or generator changes, so goldens are untouched.

Checklist

• Tests added/updated for the change (version_test)
• bazel test //... and (cd codegen && gradle build spotlessCheck) pass locally (Beast/benchmark excluded per docs)
• Formatting clean
• Architectural decisions recorded as an ADR (not applicable — version/doc reconciliation)

🤖 Generated with Claude Code

https://claude.ai/code/session_01SyQAo21Pv6GYhHrkbQj8xQ

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