Replace string concatenation with ts-dedent in mcpHandler tool descriptions

Every MCP tool/resource description and multi-clause .describe() field in
this file was built via chains of "..." + "..." string concatenation,
which is noisy to read and edit compared to a plain paragraph. Switched all
of them to ts-dedent tagged template literals instead — dedent strips the
common leading indentation regardless of how the source is nested, so the
template can be indented normally without polluting the output string.

Every converted string was verified byte-for-byte identical to its
pre-conversion value before and after editing: first via a standalone
script comparing old vs. new definitions, then via a temporary jest test
that instantiated the real McpHandler and asserted the runtime-registered
tool/field descriptions matched the originals exactly (both tests deleted
after passing). This caught one real bug along the way — a literal '\n\n'
inside vault_patch's content description (text instructing the model on
how to type a literal escape sequence) initially got converted into an
actual newline instead of staying as the two-character escape text.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>