Finish registry-based emitter integration after #1153 #1269

Problem

Microcosm #1153 merged before the external emitter package was published and before final startup integration was complete.

• The workspace resolves emitter through a Git source override at an older revision. Published wheel metadata instead requires microcosm-emitter==0.1.0, which ordinary public-PyPI installations cannot currently resolve.
• The build adapter explicitly requests a three-second startup timeout and discards safe startup reason/exit-code diagnostics. Updating the dependency alone will not adopt emitter Define and enforce a release artifact contract for populace-us (releases differ in files and manifest schema) #11's fixes.
• Documentation still describes the extraction as unmerged, and the adapter constructor lost its public parameter annotations.
• Existing wheel checks inspect archive contents; the final released dependency has not been qualified in a normal clean installation.

The merged lockfile checksum is currently correct. No revert, production deployment or package publication is authorized by this issue.

Correction

• Publish and verify an emitter distribution containing merged emitter Define and enforce a release artifact contract for populace-us (releases differ in files and manifest schema) #11 and Publish a latest.json release pointer on policyengine/populace-us #9. Confirm Trusted Publisher and release environment readiness first. Its existing release workflow also publishes the Orrery reader to npm, so publication authorization must cover that separately visible output.
• Remove the Git source override and select the actual published version, using registry metadata and artifact hashes rather than fabricated lock entries.
• Regenerate the lockfile and approved worker-identity checksum.
• Use the emitter's shared startup default, preserve explicit overrides, and retain sanitized failure reasons and exit codes while keeping failed startup nonfatal.
• Restore adapter types and replace stale draft/extraction documentation.
• Add default/override, diagnostic/redaction, disabled-client and cleanup regressions; run affected tests on Python 3.13 and 3.14.
• Verify the final Microcosm wheels with the real downloaded emitter wheel in a clean installation, including metadata, registered modules, startup, outcomes, graph requests and cleanup.
• Open a new corrective draft PR from refreshed main with Fixes #THIS_ISSUE as the first description line; do not merge until publication and installed-package qualification are complete.

No optional dependency, direct Git replacement, private-index workaround, raw SQL, database fallback, or new hosted collector is part of this correction.