refactor(fleet): dispatch suites with rc inputs and drop parent repin and floor gate

[joshua-temple]

Problem

The fleet pinned every example repo to the candidate from a central parent repin job before fan-out, and a floor-check job (plus the daily suite-tooling-floor workflow and its script) guarded suite bootstrap pins. With the suites now able to self-repin from a dispatched version, that central machinery is redundant: it duplicates work each suite can do on its own main, and the floor gate is superseded by the release-triggered bootstrap-pin bump.

Change

• resolve now also peels the resolved rc tag to its commit sha and exposes it as a second output cascade_version_sha (guarded so an empty version stays a clean no-op).
• Each lane (primary, dependents, heavy, remainder) gates on resolve instead of the parent repin, and forwards cascade_version + cascade_version_sha to its dispatch-suite step so the suite self-repins to the version under test.
• Deleted the parent repin job, the floor-check job, .github/scripts/check-suite-tooling-floor.sh, and .github/workflows/suite-tooling-floor.yaml.
• aggregate drops the floor-check/repin needs, env vars, and table rows while preserving the resolve check, the candidate-version check, the per-lane success-or-skipped rule, and the fail-closed no-lane-ran guard.
• dispatch-suite NOTE corrected to say the version is forwarded only when non-empty.
• Docs (release-orchestration) updated to the self-repin model and the release-triggered bootstrap-pin bump.

Verification

• actionlint clean on the fleet and bootstrap-pin workflows.
• No dangling repin-job / floor-check / suite-tooling-floor references remain (only the new self-repin vocabulary).
• go build ./..., go test ./... (2364 passing), and golangci-lint run ./... all clean.
• Docs site builds (17 pages).