refactor: MERGE trapfall-search into trapfalld (consolidate 9 to 6 crates)

[ajianaz]

What

Merge trapfall-search crate (40 LOC) into trapfalld. The crate is a thin pass-through — 2 function calls delegating to trapfall-db backend methods.

Why

BMAD CTO+COO consensus: 40 LOC doesn't justify a crate boundary. The doc comment says "kept as separate crate for organisational clarity and future search-backend extensions (FTS5, Postgres trigram)." But right now it uses LIKE wildcards, not even FTS5. The abstraction is premature — it's organizational noise, not clarity.

Goal: Consolidate workspace from 9 → 6 crates.

Changes

1. Move the 2 search functions from trapfall-search/src/lib.rs into trapfalld (inline or small module)
2. Update any references in trapfalld that import from trapfall-search
3. Remove trapfall-search/ directory
4. Remove from workspace members and dependency lists
5. Verify search endpoint still works

Testing

• cargo build --workspace — must pass
• cargo test --workspace — all 231 tests must still pass
• Verify /api/issues?q=... search endpoint returns correct results

[ajianaz]

Completed in PR #305 — trapfall-search merged into trapfalld as search.rs module.