feat(core): enable clippy::unnecessary_wraps (#160)

[tupe12334]

What

Enables the clippy::unnecessary_wraps lint by promoting it to deny in core/Cargo.toml, continuing the project's incremental lint-ratcheting policy (one lint promoted per PR).

The single violation it surfaces

run_validate() in core/src/bin/main.rs declared io::Result<bool> but always returned Ok(...) and never Err. The fallible signature was dead weight, forcing the validate command call site to handle an error case that could never occur.

Fix: changed the return type to plain bool, which:

• drops the unreachable Err(e) => … arm at the call site (now a simple if !run_validate(&root) { process::exit(1); }),
• removes the .unwrap() calls in the eight related unit tests.

Verification

cargo clippy --manifest-path core/Cargo.toml --all-targets --locked -- -D warnings   # clean
cargo test  --manifest-path core/Cargo.toml --locked                                  # 146 passed, 0 failed
cargo fmt   --manifest-path core/Cargo.toml -- --check                                 # clean

Closes #160

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🤖 This pull request was opened by the "Open issues → fix PRs (owned repos + my orgs)" routine of moadim.