fix(benchmark): remove personal SWE-bench path defaults

[beruro]

Problem

The SWE-bench Pro harness default embedded one developer's absolute macOS path. It was invalid on other machines, leaked a personal directory layout, and delayed the configuration error until filesystem access.

Solution

• Remove the personal filesystem default.
• Centralize resolution in benchmark/paths.rs with explicit precedence: caller-provided value, then ORGII_SWE_BENCH_PRO_REPO_PATH, then a typed not-configured error.
• Treat blank values as unset and trim resolved values.
• Surface the same actionable configuration error during preflight and local-Docker plan creation.
• Pass already-resolved evaluator/run-script paths into command preview instead of resolving them again.
• Cover precedence, blank handling, trimming, and error messaging with pure unit tests.

The branch is merged with the current develop; GitHub reports it mergeable.

Potential risks

• The original developer machine must now set ORGII_SWE_BENCH_PRO_REPO_PATH instead of relying on the removed implicit path. This is the intended compatibility break.
• There is not yet an in-app setting for this path; the environment variable remains the only production configuration source.
• In local_docker mode, missing configuration now fails during plan creation instead of returning a plan that fails later. The existing frontend error path handles the returned message; no DTO or wire shape changed.
• Rollback is a normal revert and restores the unsafe personal-path default. No data, schema, dependency, or persistence migration is involved.

Verification

• cargo test -p org2 benchmark::paths — PASS, 7 passed / 0 failed.
• rg -n "/Users/laptop-h|/Users/junyu" src-tauri/src/benchmark/ — PASS, no personal path remains.
• git diff --check — PASS.
• Merge of current origin/develop — PASS, no conflicts; targeted tests were run after integration.