Add 4 construct rows for characteristics with no coverage id

[johnml1135]

Summary

• PanGloss's pg-foma::conformance_coverage cross-check maps every CharacteristicKind to one or more constructs.txt identifiers. Four characteristics had no corresponding row at all, so no fixture could ever be written to exercise them by name: rewrite-rule directionality (left-to-right / right-to-left), phonological subrule-level MPR/POS gating, and stratification across more than one CharacterDefinitionTable.
• Adds one new row per characteristic, next to the closest existing related rows, in the file's existing plain-line style. No renumbering or reordering of existing rows.

Detail

• RewriteRule direction (Dir): left-to-right / RewriteRule direction (Dir): right-to-left — the existing RewriteRule Iterative/RewriteRule Simultaneous rows tag application order, not directionality; no row named direction as its own phenomenon.
• RewriteSubruleDef gating: required/excluded POS or MPR at the subrule level — the existing MPR features/groups row is morphological MprGroup territory (MprGroupAppend/MprGroupOverwrite); this is the distinct phonological-subrule gate.
• CharacterDefinitionTable: more than one table, one per stratum — the two existing CharacterDefinitionTable rows are about segmentation/pattern constructs within one table, not about multiple tables potentially disagreeing across strata.

Test plan

• Format matches the file's existing convention (one construct per line, no header changes)
• CI (if any) on this branch

🤖 Generated with Claude Code

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This change is 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.34%. Comparing base (dd8f95c) to head (4560e9e).

Additional details and impacted files

@@                  Coverage Diff                   @@
##           conformance-framework     #465   +/-   ##
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  Coverage                  73.34%   73.34%           
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  Files                        443      443           
  Lines                      37214    37214           
  Branches                    5110     5110           
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  Hits                       27294    27294           
  Misses                      8798     8798           
  Partials                    1122     1122           

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