Backend (SourceEvidenceLedger):
- appendWikiSourceTable now normalizes existing source lines in-place to
canonical "[N] Title - section - page N" format instead of skipping them
- Added replaceSourceLine helper that matches a full source line by regex
and replaces it with the canonical form
- When source lines exist without a "来源：" header, automatically insert
one so the frontend preprocessor can locate the source table
Frontend (useMarkdownRenderer):
- Added data-citation-index / data-citation-title to DOMPurify whitelist
- Added preprocessWikiCitations preprocessor: parses the canonical source
table to build an index-to-title map, replaces [n] markers in the answer
body with clickable <a> links, and wraps entire source-table rows so the
full line is clickable
- Integrated into the render pipeline after wikilink substitution and
before Marked parsing
Frontend (useGlobalWikilinkClick):
- Extended the click delegation selector to match both .wiki-link and
.wiki-citation elements
- Title extraction falls back: data-citation-title || data-wiki-title
Tests: added three test cases for source-line normalization, idempotency,
and automatic header insertion
