feat(bridge): PreToolUse decision file warning (GH-333)

[fagemx]

Summary

• Add decision_warning.rs with glob-matching engine that checks whether an edited file is governed by active decisions
• Integrate into dispatch_pre_tool_use as a fourth additionalContext source, triggered only on Edit tool calls
• Session-scoped DECISION_CACHE with 120s TTL ensures repeated PreToolUse calls avoid re-querying SQLite (PERF-01 < 100ms)

Boundary Compliance

• BOUNDARY-01: No DecisionRow import in edda-bridge-claude — only DecisionView
• BOUNDARY-02: Reads via query_active_with_paths() which uses to_view() internally
• PERF-01: Timing instrumented via tracing::debug!("decision_warning_ms=...")

Test plan

• test_no_decisions_returns_none — empty ledger returns None
• test_no_matching_paths_returns_none — non-matching glob returns None
• test_matching_glob_returns_warning — matching glob returns formatted warning
• test_multiple_matches — two matching decisions both appear in warning
• test_matches_any_path_normalization — backslash paths match forward-slash globs
• test_format_warning_empty_reason — empty reason omits trailing separator
• cargo clippy -p edda-bridge-claude --all-targets — zero warnings
• grep -rn "DecisionRow" crates/edda-bridge-claude/ — 0 code results (only comment)

Closes #333

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