feat: add graphile-ltree plugin — auto-detect ltree columns, folder fields, containment/glob filters

[pyramation]

Summary

Adds graphile-ltree — a PostGraphile v5 plugin for ltree columns with two presets:

GraphileLtreePreset (base) — raw ltree operators on the native LTree scalar:

• isAncestorOf (containment <@), isDescendantOf (@>), matchesGlob (lquery ~)

GraphileFolderPreset (extends base) — folder-oriented layer:

• Renames ltree columns via @name tag: path → pathTree (dot-delimited raw ltree)
• Adds virtual folder field with clean name: path (slash-delimited, e.g. /projects/alpha/docs)
• Registers folder operators: within, ancestorOf, glob (accept slash paths)
• Glob semantics: * = single level, ** = recursive

Both presets auto-detect ltree columns by scanning pgRegistry — no smart tags or config needed. Uses ltree_helpers.to_query() when available, inline SQL fallback otherwise.

ConstructivePreset now uses GraphileFolderPreset for the full folder experience.

# Display
{ allFiles { nodes { path pathTree filename } } }
# path = \"/projects/alpha/docs\", pathTree = \"projects.alpha.docs\"

# Folder operators
allFiles(where: { pathTree: { within: \"/projects/alpha\" } })
allFiles(where: { pathTree: { glob: \"/projects/*/docs\" } })

New package at graphile/graphile-ltree/ with 5 plugins, 13 integration tests, added to CI matrix.

Review & Testing Checklist for Human

• Verify path returns slash-delimited values and pathTree returns dot-delimited raw ltree
• Verify folder operators (within, glob, ancestorOf) correctly accept slash-delimited paths
• Verify * wildcard matches single level only (not recursive) — this was a bug that's now fixed
• Check that auto-detection works on any table with ltree columns without manual configuration

Notes

Depends on pgpm-ltree-helpers module (PR #1055, merged) for server-side path conversion. The glob→lquery conversion fix (* → *{1}) is also applied in the upstream helpers (constructive-db PR #1007, pgpm-modules PR #65).

Link to Devin session: https://app.devin.ai/sessions/ffa3ed8652fc412f976accbdc229c88d
Requested by: @pyramation

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