refactor: extract applescript_escape into shared escape module

[Wirasm]

Summary

• Move applescript_escape from terminal::common::escape to a new top-level escape module in kild-core
• Eliminates cross-domain dependency where notify reached into terminal internals for a general-purpose string escaping function
• Fix pre-existing unused imports in git/health.rs exposed by cargo fmt

Closes #327

Test plan

• cargo fmt --check passes
• cargo clippy --all -- -D warnings passes
• cargo test --all passes (803 tests)
• cargo build --all succeeds

[Wirasm]

PR Review Summary

Critical Issues (0 found)

None.

Important Issues (0 found)

None.

Suggestions (2 found)

Agent	Suggestion	Location
pr-test-analyzer	Add explicit test for \r carriage return escaping (implemented but not tested)	crates/kild-core/src/escape.rs:8
pr-test-analyzer	Add test for combined escape sequences to prevent replacement-order regressions	crates/kild-core/src/escape.rs:4-9

Strengths

• Clean extraction — eliminates cross-domain dependency (notify → terminal) without changing behavior
• Tests moved with the function, maintaining coverage
• Unused imports in git/health.rs cleaned up properly
• All error handling in affected code paths meets standards — no silent failures
• No documentation updates needed (internal implementation detail)

Documentation Updates

None required — no docs reference the old module path.

Verdict

READY TO MERGE

All 4 review agents passed. The two suggestions are minor test coverage improvements (not blockers).

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Reviewed by: code-reviewer, docs-impact-agent, pr-test-analyzer, silent-failure-hunter