refactor(app): clarify application and binary roles

Rename the application Cargo package from irtt-cli to irtt-rs
(crates/irtt-cli -> crates/irtt-app), and hard-rename its scriptable
client binary from irtt-cli to irtt-client, now that the application
also ships a first-class server and the old name reads as an umbrella
CLI for both roles.

Give each dedicated binary (irtt-client, irtt-tui, irtt-server) its
own entry point instead of funneling through the multicall
dispatcher's argv0/subcommand logic, so a dedicated binary only links
the applet code for the role it implements and always runs that role
regardless of the name it's invoked or copied under. irtt-rs remains
the feature-selectable multicall dispatcher and is now the only binary
that inspects argv0 or subcommands.

Move future application releases to the irtt-rs/vX.Y.Z tag namespace
(regenerated via `dist generate`), and bump the application package to
0.6.0 as a breaking distribution change. Library crate versions are
unaffected.

CHANGELOG.md

@@ -88,6 +88,17 @@ release. The format is loosely based on
 - `LateReplyMode` (`Measure` / `CountOnly`) lets a consumer choose whether replies that arrive after their probe is considered late are still fully measured into the running statistics or only counted, without affecting the other samples.
 - `StatsConfig::estimated_retained_bytes(probe_count)` gives callers an API to estimate the memory a stats configuration will retain for a given probe count, ahead of actually running a session (used by `irtt-cli`'s multi-target memory-usage warning, see below).
 
+## irtt-rs
+
+### 0.6.0
+
+#### Changed
+
+- The application Cargo package was renamed from `irtt-cli` to `irtt-rs`, moving to `crates/irtt-app`. This is the application distribution package that produces the `irtt-rs`, `irtt-client`, `irtt-tui`, and `irtt-server` binaries; it is unrelated to the reusable `irtt-client` library crate, which keeps its existing name and version.
+- The `irtt-cli` executable was hard-renamed to `irtt-client` to avoid reading as an umbrella CLI now that the application also ships a first-class server. There is no `irtt-cli` compatibility binary or alias.
+- Dedicated binaries now have role-specific entry points (`irtt-client`, `irtt-tui`, `irtt-server`) instead of all funneling through the multicall dispatcher's argv0/subcommand logic. Each dedicated binary always runs its own role regardless of the name it is invoked or copied under, and no longer links code for the other applet roles it doesn't implement. The `irtt-rs` binary remains the feature-selectable multicall dispatcher and is the only binary that inspects argv0 or subcommands.
+- Future application releases move to the `irtt-rs/vX.Y.Z` tag namespace (previously `irtt-cli/vX.Y.Z`); see [Releasing](#releasing).
+
 ## irtt-cli
 
 ### 0.5.0
@@ -125,6 +136,8 @@ rather than in lockstep. Each crate's release is tagged as `<crate>/vX.Y.Z`
 from. `irtt-proto`, `irtt-client`, `irtt-server`, and `irtt-stats` are
 libraries published to [crates.io](https://crates.io); their tags exist to
 identify the exact source for a given crates.io release and do not produce a
-GitHub Release. `irtt-cli` is the only crate with prebuilt binary artifacts:
-pushing an `irtt-cli/vX.Y.Z` tag triggers [cargo-dist](https://opensource.axo.dev/cargo-dist/)
-to build and publish a GitHub Release with platform binaries.
+GitHub Release. The application package (`irtt-cli` through 0.5.0, `irtt-rs`
+from 0.6.0 onward) is the only package with prebuilt binary artifacts: pushing
+an `irtt-rs/vX.Y.Z` tag triggers [cargo-dist](https://opensource.axo.dev/cargo-dist/)
+to build and publish a GitHub Release with platform binaries. The historical
+`irtt-cli/v0.5.0` tag remains as released; it is not rewritten or replaced.