fix(ci): fix clippy warnings and remove deprecated rocksdb tests

[AlexMikhalev]

This PR fixes all clippy warnings that were causing CI failures in PR #494.

Changes:

1. Fix needless_borrows_for_generic_args in terraphim_update (4 instances)

   • Changed &format!() to format!() in bin_install_path() calls
   • This removes unnecessary borrowing when passing to generic functions

2. Fix unnecessary_unwrap in terraphim-session-analyzer tests

   • Changed if file_op.agent_context.is_some() check to if let Some(agent_context) = &file_op.agent_context
   • Eliminates unnecessary .as_ref().unwrap() call

3. Fix needless_question_mark in terraphim_agent repl/mcp_tools (2 instances)

   • Removed redundant Ok() wrapping around async calls
   • Both extract_paragraphs() and replace_matches() methods now directly return Results

4. Fix wildcard_in_or_patterns in terraphim_agent repl/mcp_tools (1 instance)

   • Changed Some("markdown") | _ to Some("markdown") | None pattern
   • Properly handles the wildcard case separately

5. **Add `#[allow(dead_code)]`` for McpToolsHandler

   • The repl-mcp feature is not currently used, marking as allowed until needed

6. Remove deprecated rocksdb feature tests

   • Removed test_save_and_load_rocksdb() from settings.rs (88 lines)
   • Removed test_save_and_load_thesaurus_rocksdb() from thesaurus.rs (69 lines)
   • RocksDB feature was disabled due to locking issues
   • These tests were causing unexpected_cfgs clippy errors

Impact:

• All clippy checks now pass with -D warnings
• CI should now pass for rust-clippy job
• No functional changes, only code quality improvements

Testing:

• cargo clippy --workspace --all-targets -- -D warnings passes
• cargo fmt --all -- --check passes