[#99] Resolve ContentDirectory references when content files lack the .cf extension

[SkowronskiAndrew]

Summary

Fixes a break in the ContentLayout reference resolution added under #99, found while
analyzing a real Addressables-built content directory.

ContentLayout reference resolution keyed each content file as <contenthash>.cf, but
the analyzed file was keyed by its actual on-disk name. In a build whose archive
entries omit the extension (the entry is just <contenthash>, not <contenthash>.cf)
the two keys never matched. Resolution then fell through to the .cfid placeholders in
the file's external reference table, producing phantom .cfid rows in serialized_files
(with NULL archive) and a flood of dangling_refs — none of which should happen when a
matching ContentLayout.json is supplied. The extension is informational (the loader
identifies content by hash), so a build is free to omit it, and this tool must handle
both forms.

Changes

• Add ContentFileDependencyMap.NormalizeFileName — strips a trailing .cf
  (case-insensitive on the extension) so a content file resolves to the same
  serialized-file id whether or not the extension is present on disk. The name's case is
  otherwise preserved, matching the case-sensitive serialized-file name matching from Match SerializedFile names case-sensitively #106.
  Non-content files never end in .cf, so it is a no-op for them.
• Apply it at every site where a content-file name becomes a serialized-file id key:
  the analyzed file's id, the dependency-map lookup, and the external-reference fallback
  name (SerializedFileSQLiteWriter); the dependency-map keys and resolved dependency
  names (ContentLayoutSQLWriter.PopulateContentFileDependencies); and the layout link
  id (ContentLayoutSQLWriter.LinkSerializedFiles).
• The layout-only placeholder row keeps the canonical <hash>.cf display name, since
  that file was never seen on disk; only the id key is normalized.

.resS/.resource were reviewed and need no change: content directory builds reference
them via cah:/<hash> and the tool never opens them by filename, so their extensions
are already irrelevant.

Testing

• dotnet test — full suite green (259 passed), including the AnalyzeContentLayoutTests
  that cover the .cf-extension reference build (unchanged behavior).
• Manual verification against the reported real-world build (an Addressables content
  directory packed into .archive files with extensionless entries):
  • .cfid rows in serialized_files: 0 (was: several)
  • dangling_refs: 8, all targeting unity default resources — the expected
    built-in case (was: many, spanning content files)
  • the only NULL-archive serialized_files row is the unity default resources
    built-in
  • every non-built-in content_layout_serialized_files entry links to its real
    analyzed row (0 unlinked)

No automated fixture for the extensionless case is added here; a no-extension archive
reference build will be added to TestCommon/Data separately.

[Copilot]

Pull request overview

This PR fixes ContentDirectory reference resolution when content files in archives omit the .cf extension by normalizing content-file identifiers so analyzed files and ContentLayout-derived references resolve to the same serialized-file ids regardless of on-disk naming.

Changes:

• Added ContentFileDependencyMap.NormalizeFileName to canonicalize content-file keys (lowercase + strip trailing .cf).
• Updated serialized-file id assignment, dependency-map lookup, and external-reference fallback naming to use the normalized key.
• Updated ContentLayout dependency-map population and layout-to-core linking to use normalized keys while preserving canonical "<hash>.cf" display names for layout-only stub rows.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
Analyzer/Util/ContentFileDependencyMap.cs	Introduces content-file name normalization to make ids extension-agnostic.
Analyzer/SQLite/Writers/SerializedFileSQLiteWriter.cs	Uses normalized content-file keys when assigning ids and resolving external references.
Analyzer/SQLite/Writers/ContentLayoutSQLWriter.cs	Normalizes dependency-map keys/resolved names and uses normalized keys when linking layout entries to analyzed serialized files.

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