feat(error): add shared bail! and ensure! macros to ironrdp-error

[Greg Lamberson (glamberson)]

Refs #1257.

Implements Change 3 from the proposal in #1257. Adds workspace-shared bail! and ensure! macros to ironrdp-error so call-site verbosity for typed errors matches anyhow::bail!/anyhow::ensure!.

What changes

• bail!(kind) — empty context.
• bail!(context, kind) — explicit &'static str context.
• bail!(context, kind, source: source) — explicit context plus a chained source error.
• ensure!(condition, kind) — empty context.
• ensure!(condition, context, kind) — explicit context.

Both macros are #[macro_export]ed at the ironrdp-error crate root and use $crate::Error::new(...) for hygiene. The kind type is inferred from the enclosing function's return type (which must be Result<_, Error<Kind>> or any alias resolving to it).

Composition with #[track_caller]

Once Change 2 (#1262) lands and Error::new is annotated #[track_caller], these macros automatically capture the location at the macro use site (because the Error::new call expanded inside the macro is the caller of its own constructor, and #[track_caller] resolves to the macro's caller). This is the intended composition: Change 2 supplies the location, Change 3 supplies the call-site ergonomics, both compose without coordination.

No deprecation of per-crate macros

The existing per-crate constructor macros (decode_err!, encode_err!, pdu_other_err!, etc.) serve a different ergonomic pattern: they construct an error to be passed to ? or .map_err(...), rather than performing an early return. The shared bail!/ensure! are additive — they cover the early-return patterns that previously required hand-written return Err(Error::new(...)) boilerplate. The per-crate constructor macros remain useful for .map_err(decode_err!(...)) style and are not deprecated by this change.

Public API impact

Strictly additive. Two new exported macros at the ironrdp-error crate root. No changes to existing types, traits, or methods.

no_std verification

All three feature combinations of ironrdp-error build cleanly:

• cargo check -p ironrdp-error --no-default-features
• cargo check -p ironrdp-error --no-default-features --features alloc
• cargo check -p ironrdp-error --features std

The macros use only fully-pathed std-free constructs (::core::result::Result::Err, $crate::Error::new), so they work identically across feature combinations.

xtask verification

• cargo xtask check fmt: clean
• cargo xtask check lints: clean
• cargo xtask check locks: clean
• cargo xtask check typos: clean
• cargo xtask check tests: clean

Diff size

1 file changed, +56 lines, no deletions.