Fix Story Map links for file-only locations

[hanley-development]

Summary

Fixes Story Map nodes for events whose location value is a file path without a :line suffix.

Previously, Story Map only linked location values that looked like path/to/file.py:42. Events with locations like src/projectmem/commands/visualize.py could render as disconnected floating event nodes even though the location pointed to a real file.

Changes

• Adds a small path-detection helper for Story Map location values.
• Links file-only locations, such as src/projectmem/commands/visualize.py, to their file node.
• Preserves existing support for file:line locations.
• Normalizes Windows-style paths like .\src\projectmem\cli.py.
• Links existing directory locations with a trailing slash, such as tests/.
• Leaves descriptive/non-path locations unlinked, such as projectmem pre-commit hook.

Verification

• python -m pytest tests\test_visualize.py -q
• python -m pytest -q

Notes

This is a visualization-only fix. It does not change how events are recorded or stored; it only improves how existing location values are interpreted when building the Story Map graph.