fix(DE-115): finalize P01 — matches_pattern import + cleanup whitespace

Update common.py to import matches_pattern from core.filters (replacing
_matches_pattern re-export). Remove trailing blank lines left by
create_title_slug deletion. Mark phase-01 tasks and exit criteria done.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: davidlee

supekku/scripts/lib/decisions/creation.py

@@ -52,7 +52,6 @@ def generate_next_adr_id(registry: DecisionRegistry) -> str:
   """
   return next_sequential_id(registry.collect(), "ADR")
 
-
 def build_adr_frontmatter(
   adr_id: str,
   title: str,

supekku/scripts/lib/policies/creation.py

@@ -52,7 +52,6 @@ def generate_next_policy_id(registry: PolicyRegistry) -> str:
   """
   return next_sequential_id(registry.collect(), "POL")
 
-
 def build_policy_frontmatter(
   policy_id: str,
   title: str,

supekku/scripts/lib/standards/creation.py

@@ -51,7 +51,6 @@ def generate_next_standard_id(registry: StandardRegistry) -> str:
   """
   return next_sequential_id(registry.collect(), "STD")
 
-
 def build_standard_frontmatter(
   standard_id: str,
   title: str,