Adds non-repo bootstrap and publish flows

### Added
- Non-repository startup flow offering init-only or init+publish paths.
- Provider selection for publishing (GitHub via CLI, Gitea via HTTPS API).
- Gitea repository creation and initial push over HTTPS with configurable base URL, owner, and token defaults.
- Root README and documentation updates describing bootstrap flow and environment variables.

doc/architecture.md

@@ -8,8 +8,12 @@
 
 - `git-tui`:
   - Initializes and runs the curses application loop.
+  - Handles startup bootstrap for non-repository directories.
   - Renders a menu-driven UI with keyboard navigation.
   - Executes Git subprocess commands and displays command output.
+  - Executes provider-specific publication for new remote repositories:
+    - GitHub via `gh` CLI.
+    - Gitea via HTTPS API and token-authenticated initial push.
   - Implements file selection for staged and unstaged operations.
 
 ## Public API and Contracts
@@ -17,8 +21,11 @@
 - Command entry point: `git-tui` executable script.
 - Runtime contract:
   - Must be executed in a terminal that supports curses.
-  - Must be run from a directory inside a Git working tree.
+  - Must be run from a writable project directory.
   - Requires `git` to be installed and available in `PATH`.
+  - Requires `gh` in `PATH` only for GitHub publication.
+  - Requires Gitea API token for Gitea publication.
+  - Runs Git subprocesses in non-interactive mode to avoid terminal credential prompt deadlocks.
 
 ## Data Model