refactor(plugins)!: typed PluginCellValue for binary cells

[datlechin]

Summary

Fixes #1188 by replacing the implicit String-as-bytes contract with a typed PluginCellValue (.null / .text(String) / .bytes(Data)) that flows end-to-end from plugin to display to SQL emission. The visible 48-byte BYTEA value \xd38ce566...534f now displays as 0xD38CE566...534F with 48 bytes, and edits to high-byte binary cells round-trip correctly through the database.

• Read pipeline: PluginQueryResult.rows: [[PluginCellValue]], QueryResult.rows: [[PluginCellValue]], Row.values: ContiguousArray<PluginCellValue>. Every driver plugin (PostgreSQL, MySQL, SQLite, MSSQL, Oracle, DuckDB, Cassandra, MongoDB, DynamoDB, BigQuery, etc.) emits .bytes(Data) for its native binary column types.
• LibPQByteaDecoder: parses libpq text-format BYTEA (\xHH... hex and \nnn octal escape) into Data at the plugin boundary.
• Edit + save pipeline: RowChange.cellChanges, RowChange.originalRow, ParameterizedStatement.parameters, and SQLStatementGenerator all consume typed PluginCellValue. .bytes(Data) parameters survive through the adapter and bind via libpq's binary parameter format (paramFormats[i] = 1) instead of being UTF-8-re-encoded text. The same path is in place for MySQL/MariaDB blob binding and SQLite sqlite3_bind_blob.
• Hex editors: BlobHexEditorView (sidebar) and HexEditorContentView (popover) commit Data through new typed paths (commitBytes callback / setFieldToBytes / commitBinaryEdit) so a hex edit produces .bytes(Data) directly, not a Latin-1 String wrap.
• Click routing: column-type wins over content heuristics in DataGridView+Click.swift. Binary bytes that incidentally contain \n, \f, or { no longer route through the multi-line/JSON text editor.

This rides the still-unreleased PluginKit ABI v11; no version bump.

Test plan

• LibPQByteaDecoder* suites (26 tests): hex format edge cases, octal escapes, encode round-trip across all 256 byte values, exact-value regression for Wrong binary hex value #1188.
• BlobFormattingService* suites (13 tests): byte count, compact hex, hex dump, editable hex, parse hex.
• SQLStatementGeneratorBinaryTests (4 tests): .bytes newValue produces Data parameter (not String) on UPDATE/INSERT; .null produces nil (not String); exact Wrong binary hex value #1188 48-byte value round-trips through the SQL emission as Data.
• Manual: opened _sqlx_migrations rows, confirmed display + sidebar + hex editor all show 48 bytes and the correct hex.
• User to run full xcodebuild test.
• User to verify cross-driver: MySQL VARBINARY edit + save, SQLite BLOB edit + save.