Fix code quality issues: sentence case, promise handling, deprecated functions, settings headings

[Copilot]

• Explore the codebase and run ESLint to identify all issues
• Fix orphaned ; in settings-tab.ts (replaced with heading, then removed redundant plugin-name heading)
• Fix sentence case: "Join every N lines" → "Join every n lines" in main.ts
• Fix Promise-returning function in void context (main.ts L341) - updated InputModal.onSubmit type to unknown
• Fix unawaited promise: this.saveSettings() → void this.saveSettings().catch(...) (main.ts L799)
• Fix deprecated unescape/escape in encode.ts (replaced with TextEncoder/TextDecoder)
• Remove unused vi import in lines.test.ts
• Update ESLint config to allow proper acronyms/brands (UTC, ISO, Unix, GUIDs)
• Fix no-undef for btoa/atob in ESLint config (added browser globals)
• Fix unsafe assignment in main.ts L847 and encode.ts
• Fix floating promises in InputModal at call sites (submitAndCatch helper with rejection logging)
• Remove eslint-plugin-obsidian (wrong package), fix ESLint → 9.x and @eslint/json → 0.14.0 to match plugin peer deps; regenerate package-lock.json so npm ci works
• Fix "N (lines per group)" label → "Number of lines per group" and notice to "Enter a positive integer."
• Use { fatal: true } in TextDecoder for base64Decode to preserve fallback behavior on invalid UTF-8
• Verify all ESLint checks pass (0 errors)
• Verify all 135 tests pass
• Verify build succeeds
• Verify npm ci succeeds

Original prompt

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This section details on the original issue you should resolve

<issue_title>Issues detected in code quality </issue_title>
<issue_description>A scan of the plugin code's revealed the following issues:

Required

[1][2][3][4][5][6]
Use sentence case for UI text.
[1]
Promise-returning function provided to property where a void return was expected.

[1]
Promises must be awaited, end with a call to .catch, end with a call to .then with a rejection handler or be explicitly marked as ignored with the void operator.
[1][2][3][4][5]

For a consistent UI use new Setting(containerEl).setName(...).setHeading() instead of creating HTML heading elements directly.

[1]
unescape is deprecated. A legacy feature for browser compatibility

[1]
escape is deprecated. A legacy feature for browser compatibility

Optional

[1]
'vi' is defined but never used.

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To run these checks locally, install the eslint plugin in the project. Run and fix before commiting changes.</issue_description>

<agent_instructions>Fix and check before committing all the problems redacted in the issue.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Issues detected in code quality  #8

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[Copilot]

Pull request overview

Addresses ESLint and API deprecation findings in the Obsidian Text Tools plugin by adjusting UI text, improving promise/lint safety, modernizing Base64 encoding/decoding, and aligning settings UI structure with Obsidian’s Setting heading API.

Changes:

• Modernize Base64 encode/decode to use TextEncoder/TextDecoder and tighten some type annotations.
• Update UI strings for sentence case and refactor settings headings to use Setting(...).setHeading().
• Improve promise-handling lint compliance (async onSubmit support, explicit ignored promises) and add ESLint flat config + dependencies.

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
main.ts	Sentence-case updates, promise handling change for settings persistence, and safer typing around settings loading.
src/modals/InputModal.ts	Broadens onSubmit typing to allow async callbacks and marks returned promises as intentionally ignored.
src/settings-tab.ts	Switches settings section headings to Obsidian’s Setting(...).setHeading() pattern and tweaks descriptions.
src/transforms/encode.ts	Replaces deprecated escape/unescape Base64 shim with TextEncoder/TextDecoder; minor type-safety improvements.
src/transforms/lines.test.ts	Removes unused vi import.
eslint.config.mjs	Adds ESLint flat config using eslint-plugin-obsidianmd with sentence-case rule customization.
package.json	Adds ESLint-related dev dependencies to support the new lint configuration.