refactor: implement component-based architecture for enhanced maintainability

- Reorganize directory structure into core/, features/, and themes/
- Colocate application Nix logic, configs, scripts, and theme overrides
- Implement 'Inversion of Control' for theming: apps now pull theme-specific layouts
- Update flake.nix and shared library paths to match the new structure
- Document the new Feature-Centric architecture in README.md

core/home/config/starship.toml

@@ -0,0 +1,32 @@
+add_newline = true
+command_timeout = 200
+format = "[$directory$git_branch$git_status]($style)$character"
+
+[character]
+error_symbol = "[✗](bold cyan)"
+success_symbol = "[❯](bold cyan)"
+
+[directory]
+truncation_length = 2
+truncation_symbol = "…/"
+repo_root_style = "bold cyan"
+repo_root_format = "[$repo_root]($repo_root_style)[$path]($style)[$read_only]($read_only_style) "
+
+[git_branch]
+format = "[$branch]($style) "
+style = "italic cyan"
+
+[git_status]
+format     = '[$all_status]($style)'
+style      = "cyan"
+ahead      = "⇡${count} "
+diverged   = "⇕⇡${ahead_count}⇣${behind_count} "
+behind     = "⇣${count} "
+conflicted = " "
+up_to_date = " "
+untracked  = "? "
+modified   = " "
+stashed    = ""
+staged     = ""
+renamed    = ""
+deleted    = ""