Refine Introduction wording and add two more verified citations ...

- Add wang2026 (USCNet) and hibi2013 (IVUS history review) to
  references.bib after reading the full PDFs; cite them for KSCNet's
  originating kidney-stone-classification architecture and for the
  claim that IVUS can visualize vessel wall/plaque condition,
  respectively.
- Drop "microvascular spasm" as a contributing factor from the
  no-reflow definition, trim an editorializing clause after the
  attenuated-plaque finding, and rephrase the IVUS-focus sentence as
  the paper's own rationale rather than a general background claim.
- Remove the unsupported vasodilator-treatment-limitations sentence
  and the citation-needed marker on preventive-measures (distal
  protection devices/prophylactic vasodilators), per review: none of
  the added source papers support the former, and the latter is
  standard clinical practice not requiring a citation.
- Generalize the poor-prognosis sentence (previously citing specific,
  unsupported outcomes) to a claim not requiring a citation.

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

Wire up references.bib and verify citations against source PDFs ...

- Add citations/ folder holding the cited papers' PDFs (babapoor2022,
  wu2011, nishi2021), documented in CLAUDE.md so cite keys can be
  filled in/verified directly from the source paper instead of guessed.
- Fill in references.bib entries for all three keys with real
  bibliographic data, and drop a stray "@TODO" in the header comment
  that was making bibtex misparse the file as a malformed entry.
- Switch main.tex from the template's placeholder internal
  bibliography to \bibliography{references}, so citations actually
  resolve (previously rendered as undefined/"?").
- Correct the Introduction's babapoor2022/wu2011 citation claims after
  reading the full papers: babapoor2022 reports separate no-reflow
  (17.1%) and slow-flow (12.9%) rates in a single-center primary-PCI
  cohort, not a general "10-20% of PCI patients" figure; wu2011's
  finding is specific to AMI patients and a composite no-reflow/
  slow-flow (TIMI <=2) endpoint, and only the amount (not presence) of
  attenuated plaque differed significantly.

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