Let /skills invocations reach the prompt skill path

The CLI still treated every /skills payload other than list/install/help as local usage text, so skills that appeared in /skills could not actually be invoked. This restores prompt dispatch for /skills <skill> [args], keeps list/install on the local path, and shares skill resolution with the Skill tool so project-local and legacy /commands entries resolve consistently.

Constraint: --resume local slash execution still only supports local commands without provider turns
Rejected: Implement full resumed prompt-turn execution for /skills | larger behavior change outside this bugfix
Rejected: Keep separate skill lookups in tools and commands | drift already caused listing/invocation mismatches
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep /skills discovery, CLI prompt dispatch, and Tool Skill resolution on the same registry semantics
Tested: cargo fmt --all; cargo clippy -p commands -p tools -p rusty-claude-cli --all-targets -- -D warnings; cargo test --workspace -- --nocapture
Not-tested: Live provider-backed /skills invocation against external skill packs in an interactive REPL

rust/crates/tools/Cargo.toml

@@ -7,6 +7,7 @@ publish.workspace = true
 
 [dependencies]
 api = { path = "../api" }
+commands = { path = "../commands" }
 plugins = { path = "../plugins" }
 runtime = { path = "../runtime" }
 reqwest = { version = "0.12", default-features = false, features = ["blocking", "rustls-tls"] }