docs: add release notes and media directory for v0.5.3

LiveReview Pre-Commit Check: vouched (iter:1, coverage:0%)

Author: LinceMathew

docs/releases/img/v0.5.3/README.md

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+# Release media for v0.5.3
+
+Drop screenshots, GIFs, and any local video files for this release into this directory.
+
+Use markdown references like: ![demo](IMG:demo.png)
+For a manual video follow-up, keep this inside an HTML comment in the release notes: <!-- VIDEO:demo.mp4 -->
+
+Raw URL base after publish:
+https://raw.githubusercontent.com/HexmosTech/git-lrc/refs/heads/main/docs/releases/img/v0.5.3/

docs/releases/v0.5.3.md

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+# Release v0.5.3
+
+Date: 2026-06-21
+
+<!--
+Release images for this version belong in: docs/releases/img/v0.5.3
+Reference files from this release folder with the placeholder syntax documented in docs/releases/img/v0.5.3/README.md.
+For manual video follow-up, keep a placeholder like <!-- VIDEO:demo.mp4 --> inside an HTML comment so release-gh can remind you after publishing.
+
+Published raw URL base: https://raw.githubusercontent.com/HexmosTech/git-lrc/refs/heads/main/docs/releases/img/v0.5.3/
+Published raw URL example: https://raw.githubusercontent.com/HexmosTech/git-lrc/refs/heads/main/docs/releases/img/v0.5.3/demo.png
+-->
+
+## Summary
+
+### Improved Onboarding Flow
+
+- New `lrc onboard` Command: Introduced a non-interactive onboarding command that natively handles API key validation, auth token exchange, backups, and atomic configuration writing with strict file permissions (0600).
+- Installer Wrappers: Refactored lrc-install.sh and lrc-install.ps1 to act as clean download wrappers that delegate validation and config generation directly to lrc onboard. Removed obsolete shell/PowerShell TOML parsing helpers.
+
+## Install and Update
+
+New install:
+
+```
+# Linux/macOS
+curl -L https://hexmos.com/ipm-install | bash && ipm i HexmosTech/git-lrc
+
+# Windows
+iwr https://hexmos.com/ipm-install-ps | iex; ipm i HexmosTech/git-lrc
+```
+
+Update:
+
+```
+lrc self-update
+```
+
+## Changes
+
+- List the most important user-facing changes.
+
+## Breaking Changes
+
+- None.
+
+## Verification
+
+- lrc --version
+- lrc --help
+
+## Known Issues
+
+- None.