feat(tags): preserve tag case with case-insensitive identity

[h4yfans]

Summary

Tags now keep the capitalization you type — #Work stays #Work — while identity stays case-insensitive: #Work and #work are the same tag with one color and one combined count (Obsidian-style). Previously every layer force-lowercased tags, including Obsidian imports.

Changes

Schema + migrations

• New nocaseText custom type (text COLLATE NOCASE) on note_tags.tag, task_tags.tag, inbox_item_tags.tag, tag_definitions.name
• Index DB migration 0019 (generated), data DB migration 0034_tag_nocase.sql (hand-written, matching existing data-DB migration convention). Data preserved; INSERT OR IGNORE collapses case-duplicate rows

Main process

• Frontmatter + inline #tag extraction preserve case, dedupe case-insensitively (first spelling wins) — this fixes the Obsidian import path
• setNoteTags / setTaskTags / sync task handler / inbox bulk-tag / app-core inbox / Raindrop importer stop lowercasing on write
• Rename/merge write the new name as typed, match case-insensitively; renameTag child rewrite is now per-row (SQL replace() is case-sensitive)
• Tag list aggregation keys by lowercase, display name keeps first-seen casing
• tag_definitions rows and sync item ids stay lowercase (stable identity keys)

Renderer

• Editor hash-tag plugins no longer lowercase while typing
• normalizeHashTags / extractInlineTags preserve case with case-insensitive dedupe
• Tag color/icon maps keyed by lowercase; all lookups lowercase the key, so case variants share one color
• Autocomplete, tag manager search, and duplicate checks compare case-insensitively

Behavior notes

• Notes previously saved in-app keep their lowercased frontmatter until re-edited or renamed (case-only renames now work in Tag Manager)
• Untouched Obsidian-vault files regain their original casing on reindex

Documentation

• apps/docs/src/user-guide/notes/properties-tags.md documents the new behavior; pnpm docs:impact --strict and pnpm docs:build pass

Test plan

• Desktop main suite: 3335 passed (runs real migrations, so 0034 is exercised)
• Desktop renderer suite: 5062 passed
• app-core: 7 passed
• typecheck:node + typecheck:web clean, ESLint 0 errors, Prettier clean
• New regression tests: case-preserve + ci-dedupe in frontmatter.test.ts, ci identity in notes.test.ts (Work+work collapse; findNotesByTag('work') finds WORK)
• Manual smoke: type #Work in editor, import an Obsidian vault with mixed-case tags

[github-actions]

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