fix: validate_schema() honors ck naming_convention on lease CHECK

[lesnik512]

Problem

validate_schema() raised a spurious RuntimeError for any deployment whose MetaData carries a SQLAlchemy ck naming_convention:

Outbox schema mismatch: missing CHECK constraint 'outbox_faststream_lease_ck' (expected 'acquired_token is null = acquired_at is null')

…even with a perfectly valid schema.

Root cause. SQLAlchemy re-templates an explicitly-named CheckConstraint through a ck convention — the given name fills the %(constraint_name)s token — so the live constraint is named e.g. ck_outbox_faststream_outbox_faststream_lease_ck, not outbox_faststream_lease_ck. The CHECK probe hard-coded the literal f"{table.name}_lease_ck", never matched the re-templated name, and reported "missing". Confirmed empirically: under a ck convention the constraint resolves to the ck_… name, while the indexes keep their literal names (the ix/uq keys only re-template auto-named indexes).

Fix

_validate_check_constraints_sync now derives the expected name from the Table object via a new _resolve_check_constraint_name — it identifies the lease constraint by its normalized predicate and returns its convention-resolved .name, falling back to the literal name only when the table carries no matching constraint (reflected/hand-built Table). The expectation now always matches what SQLAlchemy / Alembic emit from your metadata, convention or not.

Tests

• Unit (no Postgres): convention-resolved name honored (the failing case), missing-under-convention reports the resolved name, literal-name fallback for a constraint-free table.
• Integration (Postgres): builds the outbox table on a ck-convention MetaData, create_alls it, asserts validate_schema() does not raise.

Full suite: 525 passed, 100% coverage; lint (ruff + ty) clean; docs build clean.

Docs / housekeeping (same PR)

• docs/operations/alembic.md — replaced the now-misleading op.f('outbox_lease_ck') caveat (it forced a literal name the probe no longer expects under a convention) with an introspect-the-rendered-name recipe.
• architecture/dlq.md — recorded the convention-awareness invariant in the validate_schema() mechanics section.
• planning/releases/0.10.2.md — release notes (patch: bugfix only, opt-in path, no API change).
• planning/changes/active/ — removed a stale draft duplicate of the already-shipped+archived fix: actionable error for Alembic-blind schema drift #99 bundle (canonical copy remains in archive/; the active index already read _None._).

Compatibility

validate_schema() is opt-in. With no naming_convention, behavior is identical to 0.10.1. With a ck convention, validation that previously raised spuriously now passes when the DB constraint carries the convention-rendered name (created via create_all or convention-aware Alembic). No other behavior change.

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