my.pdfs: cleanup/refactor

- modernize:
  - add REQUIRES spec for pdfannots library
  - config dataclass/config stub
  - stats function
  - absolute my.core imports in anticipation of splitting core
- use 'paths' instead of 'roots' (better reflects the semantics), use get_files
  backward compatible via config migration
- properly run tests/mypy

tox.ini

@@ -37,11 +37,12 @@ commands =
 
     hpi module install my.coding.commits
 
+    hpi module install my.pdfs
+
     python3 -m pytest tests \
             # ignore some tests which might take a while to run on ci..
             --ignore tests/takeout.py        \
-            --ignore tests/extra/polar.py    \
-            --ignore tests/pdfs/test_pdfs.py \
+            --ignore tests/extra/polar.py
             {posargs}
 
 
@@ -82,6 +83,7 @@ commands =
     hpi module install my.arbtt
     hpi module install my.coding.commits
     hpi module install my.goodreads
+    hpi module install my.pdfs
 
     # todo fuck. -p my.github isn't checking the subpackages?? wtf...
     # guess it wants .pyi file??
@@ -103,6 +105,7 @@ commands =
                     -p my.arbtt                       \
                     -p my.coding.commits              \
                     -p my.goodreads                   \
+                    -p my.pdfs                        \
                     --txt-report  .coverage.mypy-misc \
                     --html-report .coverage.mypy-misc \
                     {posargs}