feat: add unique template transformation

[danielo515]

Summary

Adds a new unique transformation to template variables and a matching unique getter on ResultValue that deduplicates array items while preserving the order of first occurrence.

{{ tags | unique }}

• Arrays: duplicates are removed, order-of-first-occurrence is preserved (["foo", "bar", "foo", "baz"] → foo,bar,baz).
• Non-array values (strings, numbers, booleans, FileProxy, records): returned unchanged, since a single value is trivially unique. This keeps the transformation safe to drop on any field.
• Chainable: result.getValue('tags').lower.unique.bullets works as expected.

Fits alongside the existing slug / snake / capitalize transformations and follows the same shape (single-word, no arguments, applies to both templates and ResultValue).

Motivation: multiselect and tag fields can end up with the same option repeated. Without unique, cleaning that up required a map(...) callback or Templater glue.

Changes

• src/core/template/templateSchema.ts — add unique to the transformations valibot union.
• src/core/template/templateParser.ts — handle the unique case in executeTransformation; extract a uniqueValues helper.
• src/core/ResultValue.ts — add a unique getter that delegates to uniqueValues for arrays.
• src/core/template/templateParser.test.ts / src/core/ResultValue.test.ts — cover arrays, dedup ordering, non-array pass-through, empty arrays, and chaining.
• docs/templates.md / docs/ResultValue.md — document the new transformation and shortcut.

Test plan

• npm run test — all 220 tests pass, including the new unique cases.
• npm run build — lint, svelte-check, and production bundle all succeed (only pre-existing unused-CSS warnings remain).

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Generated by Claude Code

[greptile-apps]

Greptile Summary

Adds a unique transformation that removes duplicate array entries while preserving their first-seen order.

• Extends template parsing and validation to support unique.
• Adds a chainable ResultValue.unique getter.
• Covers array deduplication, scalar pass-through, empty arrays, ordering, and shortcut chaining.
• Documents the new template transformation and ResultValue shortcut.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete functional, security, or compatibility defects identified.

The new transformation matches the repository’s string-array value model, preserves first-occurrence ordering, leaves non-array values unchanged, and is covered across both supported APIs.

Important Files Changed

Filename	Overview
src/core/template/templateParser.ts	Adds a reusable Set-based deduplication helper and exposes it through the template transformation executor.
src/core/template/templateSchema.ts	Extends the validated transformation union with the new unique keyword.
src/core/ResultValue.ts	Adds a non-mutating, chainable getter that deduplicates array values and passes scalar values through unchanged.
src/core/template/templateParser.test.ts	Tests ordering, unchanged unique arrays, scalar pass-through, and empty-array rendering for templates.
src/core/ResultValue.test.ts	Tests primitive deduplication, rendering, empty arrays, scalar pass-through, and shortcut chaining.

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