feat(operation): add AtomicOperation::supports_hooks() probe

[bodymindarts]

What

Adds a read-only capability probe to AtomicOperation:

fn supports_hooks(&self) -> bool { false } // default

• DbOp → true
• DbOpWithTime / OpWithTime → delegate to their inner op
• default (bare sqlx::Transaction, HookOperation) → false

Why

commit_hook::<H>(&self) -> Option<&H> is the only &self window into hook state, but its None is ambiguous: it means either "this op doesn't support hooks" or "it does, but nothing of type H is registered yet." The only unambiguous support signal today is add_commit_hook, which returns Err iff unsupported — but that requires &mut and consumes a hook value.

supports_hooks() reports capability directly, with &self and no registration side effect.

Consumer

obix's new OpCursor marks a position in an op's publish buffer and reads events back before commit (for atomic cross-outbox reposts). It must fail loudly when handed an op that can't buffer (a bare sqlx::Transaction) rather than silently yield nothing. Without this probe, cursor() had to take &mut op and register an empty hook just to detect support; with it, cursor(&op) -> Result<…> stays borrow-light:

if !op.supports_hooks() {
    return Err(CursorError::HooksUnsupported);
}

Tests

tests/hooks.rs::supports_hooks_reflects_op_capability — asserts true for DbOp and its time wrappers, false for a bare sqlx::Transaction. Full hooks suite: 11 passed. cargo fmt --check clean; no new clippy warnings.

Additive and backwards-compatible (defaulted trait method). Unblocks the es-entity bump + OpCursor fail-loud behavior in obix (GaloyMoney/obix#79).

🤖 Generated with Claude Code

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Note

Low Risk
Additive defaulted trait method with narrow capability reporting; no change to commit or hook execution paths.

Overview
Adds AtomicOperation::supports_hooks(&self) -> bool so callers can tell whether an op can register commit hooks without using &mut or registering a dummy hook.

commit_hook’s None could mean “no hooks” or “nothing registered yet”; supports_hooks is unambiguous: DbOp (and time wrappers via delegation) return true, while the trait default and bare sqlx::Transaction return false.

A new integration test in tests/hooks.rs asserts that behavior for DbOp, DbOpWithTime, OpWithTime, and a raw transaction.

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