Spellchecker: resolve warnings (#42202)

## Summary of the Pull Request

This PR resolves lingering spell-check warnings and other minor issues,
allowing us to focus on newly emerging problems.

**Changes:**

- Excludes empty and binary files  
- Converts invalid dictionary entries into patterns  
- Since dictionary entries can only contain letters, `0x6f677548` was
previously ignored
- Removes unused words  
- Adds a pattern marker to ignore all code on a line  
  - `/* #no-spell-check-line */`  
  - `// #no-spell-check`  

This should reduce outstanding spellchecker warnings and suggestions to
zero.

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## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

.github/actions/spell-check/patterns.txt

@@ -1,5 +1,10 @@
 # See https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples:-patterns
 
+# marker to ignore all code on line
+^.*/\* #no-spell-check-line \*/.*$
+# marker for ignoring a comment to the end of the line
+// #no-spell-check.*$
+
 # Gaelic
 Gàidhlig
 
@@ -264,3 +269,7 @@ St&yle
 # This matches a relative clause where the relative pronoun "that" is omitted.
 # Example: "Gets or sets the window the TitleBar should configure."
 \bthe\s+\w+\s+the\b
+
+# Usernames with numbers
+# 0x6f677548 is user name but user folder causes a flag
+\bx6f677548\b