docs(readme): point installer links to GitHub Releases

[arnestrickmann]

Summary

Updates the README installer links to use GitHub Releases asset URLs instead of the R2 mirror.

We are already moving manual downloads back to GitHub Releases with this change, and the next step is switching production release asset hosting/publishing back to GitHub Releases while keeping the R2 update path available for existing users.

Notes

• Keeps the existing latest release page link unchanged.
• Does not change updater behavior or release workflows.
• Helps README/manual downloads count toward GitHub Release download totals.

Description

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Related issues

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Testing

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pnpm run typecheck, pnpm run test, and any manual testing.

Screenshot/Recording (if applicable)

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Checklist

• I kept this PR small and focused
• I ran a self-review before opening this PR
• I ran the relevant local checks or explained why not
• I updated docs when behavior or setup changed
• I added or updated tests when behavior changed, or explained why not
• I only added comments where the logic is not obvious
• I used Conventional Commits for commit
  messages and, when possible, the PR title

[greptile-apps]

Greptile Summary

This PR updates the six manual installer links in the README's installation table from the R2 mirror (releases.emdash.sh) to GitHub's releases/latest/download/ URL pattern, routing manual downloads through GitHub Releases.

• All six asset filenames are preserved exactly as-is across macOS (arm64 + x64 DMG), Windows (MSI + EXE), and Linux (AppImage + DEB).
• The existing "latest release" page link and Homebrew cask command are left untouched.
• No runtime behavior, updater logic, or release workflows are affected.

Confidence Score: 5/5

Safe to merge — only documentation links are changed, no code or workflows are affected.

All six installer URLs are updated to the standard GitHub releases/latest/download/ redirect pattern with identical asset filenames. The change is purely additive to README content and has no impact on application code, release workflows, or updater behavior.

No files require special attention.

Important Files Changed

Filename	Overview
README.md	Replaces three R2 mirror download URLs (releases.emdash.sh) with GitHub Releases latest-download URLs for all six platform installers; no structural or content changes.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[User clicks README installer link] --> B{Platform}
    B -->|macOS Apple Silicon| C["github.com/.../emdash-arm64.dmg"]
    B -->|macOS Intel| D["github.com/.../emdash-x64.dmg"]
    B -->|Windows Installer| E["github.com/.../emdash-x64.msi"]
    B -->|Windows Portable| F["github.com/.../emdash-x64.exe"]
    B -->|Linux AppImage| G["github.com/.../emdash-x86_64.AppImage"]
    B -->|Linux Debian| H["github.com/.../emdash-amd64.deb"]
    C & D & E & F & G & H --> I[GitHub Releases /latest/download/ redirect]
    I --> J[Download latest asset]

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