fix(loader): report malformed parameter directives

[cofin]

Summary

• make malformed -- param: warnings actionable in standard logging
• report the file, 1-based line number, and malformed directive in both the message and structured fields
• preserve strict-mode errors and default warn-and-skip behavior

Closes #676

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.32%. Comparing base (b475727) to head (ee0b103).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #677      +/-   ##
==========================================
- Coverage   77.34%   77.32%   -0.02%     
==========================================
  Files         476      476              
  Lines       68106    68107       +1     
  Branches     9363     9363              
==========================================
- Hits        52675    52667       -8     
- Misses      12022    12031       +9     
  Partials     3409     3409              

Flag	Coverage Δ
integration	60.89% <0.00%> (-0.04%)	⬇️
py3.10	75.64% <100.00%> (-0.01%)	⬇️
py3.11	75.65% <100.00%> (-0.02%)	⬇️
py3.12	75.66% <100.00%> (+<0.01%)	⬆️
py3.13	75.66% <100.00%> (-0.01%)	⬇️
py3.14	76.53% <100.00%> (-0.02%)	⬇️
unit	64.89% <100.00%> (+<0.01%)	⬆️

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Files with missing lines	Coverage Δ
sqlspec/loader.py	93.67% <100.00%> (+0.01%)	⬆️

... and 3 files with indirect coverage changes

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