sparkwing CLI v0.10.0

This release re-versions the runs-store schema 3 → 4 change that first
shipped, under-versioned as a patch, in v0.9.2 and v0.9.3. There is no
functional change over v0.9.3 -- v0.10.0 is the canonical, correctly
versioned home of the break and the consolidated user-facing narrative
for everything that landed since v0.9.1. The v0.9.2 and v0.9.3 sections
below are kept for the audit trail and now carry an erratum.

Changed

• store (Breaking): The runs-store schema moved from version 3 to 4,
  adding a sparkwing_meta table that backs throttle stamps and other
  small operational state. The store auto-migrates the database on open,
  so a plain CLI or controller upgrade needs no action. But a module
  that pins an older (schema-3) sparkwing and shares the same state
  database has its pre-commit / pre-push gate refuse the migrated
  database until the pin is bumped. See
  docs/migrations/v0.10.0.md
  for the upgrade steps.

Added

• cli: sparkwing maintenance runs the controller-free janitorial
  pass over the concurrency tables in the local state database: it reaps
  lease-expired holders, deletes finished and aged waiter rows, and
  bounds the concurrency cache and entries by age and size. Local runs
  trigger the same pass inline (throttled); the command forces a full
  pass now, for cron or to reclaim a database that grew while idle.
  Controllerless boxes previously had no path to this cleanup, so
  finished-run waiter rows and the concurrency tables could grow without
  bound.
• config: Pipelines accept a post_commit: trigger alongside
  pre_commit: and pre_push:. sparkwing pipeline hooks install
  writes a managed .git/hooks/post-commit for any pipeline that
  declares it; the post-commit hook is non-blocking and always exits
  zero, whereas pre-commit and pre-push still abort the git action on
  the first failing pipeline.
• cli: sparkwing version reports the binary's embedded runs-store
  schema version (schema_version in JSON, a schema: line in the
  table), so a reader confirms which schema a binary speaks without
  opening a database. The release pipeline gates published assets on it:
  a pre-publish check refuses the release if any asset embeds a
  different schema than the tagged commit.
• controller: sparkwing-controller prints a build banner at
  startup -- its version, embedded schema version, and build commit --
  and refuses to start against a state database recorded at a newer
  schema than it understands, naming both versions and the remedy.

Fixed

• sdk: Promoting queued waiters into freed concurrency slots now
  deletes and skips any waiter whose run has already finished, keeping
  FIFO order honest so a finished head can no longer wedge the live
  waiters queued behind it.
• sdk: Concurrency budgets stay correct under contention across both
  dialects: budget-mutating paths serialize on the key's row (closing a
  Postgres admit-past-capacity race), liveness decisions read the clock
  after the store lock is held (so a contended acquire can't revive an
  already-expired holder), and cancelled or re-acquired waiters drop
  their stale rows so a later release can't promote a phantom holder.