Add a subdirectories templating function

[jwilm]

Adds a subdirectories templating function which enables ConfigMap templating to be highly dynamic based on the structure of the project it's pulling from.

This is useeful when a directory has a set of homogeneous subdirectories. (e.g. subdirectories a and b both have the same set of secrets, and the subdirectory names a and b may not be known).

[infisical-cla-app]

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[greptile-apps]

Greptile Summary

This PR adds a subdirectories template function that lets ConfigMap templates enumerate immediate child directories at any path in the Infisical secret tree, enabling dynamic configuration generation when subdirectory names are not known in advance.

• Adds V1Subdirectory{Name, Path} to the model and registers a subdirectories(dir string) function in the template engine that traverses the pre-built SecretTreeNode tree, filters out leaf nodes, sorts results by name, and returns them for ranging in templates.
• The SecretTreeNode structure already allows a node to have both a Secret value and Children (e.g. a secret key at / whose name matches a folder path segment), but the new filter uses child.Secret != nil instead of len(child.Children) == 0, so any such hybrid node is incorrectly excluded from subdirectory results.
• Test coverage is solid for the happy path and empty-result cases but does not exercise the mixed secret+directory node edge case that the tree explicitly supports.

Confidence Score: 3/5

Safe to merge for common usage, but the leaf-exclusion logic is wrong for an edge case the tree already supports, and there is no test catching it.

The subdirectories function silently drops directory nodes that also carry a secret value. This is a valid tree state confirmed by an existing BuildSecretTree test, so missing directories would cause silent, hard-to-debug gaps in rendered ConfigMaps without any error surfaced to the user.

internal/template/v1/template.go — the filter condition in the subdirectories closure; internal/template/v1/template_test.go — needs a test with a node that has both Secret and Children set

Important Files Changed

Filename	Overview
internal/model/model.go	Adds V1Subdirectory struct with Name and Path fields; minimal, clean addition
internal/template/v1/template.go	Adds subdirectories template function; contains a logic bug in the leaf-exclusion filter that incorrectly skips nodes that are both a secret and a directory
internal/template/v1/template_test.go	Adds five well-structured tests for subdirectories; missing coverage for the mixed secret+directory node edge case that the tree structure explicitly supports

_{Reviews (1): Last reviewed commit: "Add a subdirectories templating function" | Re-trigger Greptile}