feat(identity): ask name/email at install, no hardcoded USER/EMAIL in the repo

- rc templates carry @USER@/@EMAIL@ placeholders; install.sh renders them
- resolve_identity: an export already in ~/.bashrc or ~/.zshrc is reused silently,
  else IDENTITY_USER/IDENTITY_EMAIL, else a prompt, else login name + empty email
- render_gitconfig generalised to render_identity_template (gitconfig unchanged)
- vimrc reads g:_author/g:_email from $USER/$EMAIL instead of hardcoded values
- README + CLAUDE.md

README.md

@@ -66,7 +66,7 @@ What it does:
 3. Moves any existing `~/.vim`, `~/.vimrc`, `~/.bashrc`, `~/.Sublivim` to `~/Oldconfig`.
 4. Clones the `syntastic` and `nerdtree` vim plugins into `~/.vim/bundle/`.
 5. Copies the tracked vim files into `~/.vim` and symlinks `~/.vimrc`.
-6. Picks the bashrc by OS: macOS → `bashrc-osx` (falls back to `bashrc-linux` if missing), everything else → `bashrc-linux`. Copies it to `~/.bashrc`. Then renders `gitconfig` into `~/.gitconfig` with that bashrc's `USER` / `EMAIL`. A different existing `~/.gitconfig` is saved as `~/.gitconfig.backup-<date>`; an identical one is left alone. It is the global level only: a repo's own `.git/config` still overrides it. `core.excludesfile` points at `~/.gitignore`, ignored by git when the file does not exist. Then deploys `tmux.conf` to `~/.config/tmux/tmux.conf` (both OSes, tmux ≥ 3.1: Ubuntu 22.04+, brew), clones [tpm](https://github.com/tmux-plugins/tpm) and fetches the listed plugins headlessly; details under [macOS](#macos) step 6, the step is the same. On Linux, `y` copies into tmux's buffer and the terminal clipboard through OSC 52; macOS uses `pbcopy`/`pbpaste`.
+6. Picks the bashrc by OS: macOS → `bashrc-osx` (falls back to `bashrc-linux` if missing), everything else → `bashrc-linux`. Renders it into `~/.bashrc` with the identity asked at the very start: a name and an email for git commits and vim headers. An `export USER=` / `export EMAIL=` already present in `~/.bashrc` or `~/.zshrc` is reused without asking, so a re-run never prompts twice; `IDENTITY_USER` / `IDENTITY_EMAIL` preset them; with no terminal attached it falls back to the login name and an empty email. The values live only in the deployed files, never in the repo. Then renders `gitconfig` into `~/.gitconfig` with the same `USER` / `EMAIL`. A different existing `~/.gitconfig` is saved as `~/.gitconfig.backup-<date>`; an identical one is left alone. It is the global level only: a repo's own `.git/config` still overrides it. `core.excludesfile` points at `~/.gitignore`, ignored by git when the file does not exist. Then deploys `tmux.conf` to `~/.config/tmux/tmux.conf` (both OSes, tmux ≥ 3.1: Ubuntu 22.04+, brew), clones [tpm](https://github.com/tmux-plugins/tpm) and fetches the listed plugins headlessly; details under [macOS](#macos) step 6, the step is the same. On Linux, `y` copies into tmux's buffer and the terminal clipboard through OSC 52; macOS uses `pbcopy`/`pbpaste`.
 7. Installs Python CLIs via `pipx` (`PyMuPDF` → `pymupdf`, `Markdown` → `markdown_py`) — skipped if `pipx` is absent.
 8. Copies the `bin/` scripts (`dt`, `dtach-router`, `claude-provider`) into `~/.local/bin`. The dtach session-resume menu ships in the deployed bashrc (both OSes), so every interactive shell offers it — including VS Code Remote-SSH terminals, which are non-login and never read `~/.profile`. The installer also strips any older dtach block left in `~/.profile` so a plain SSH login doesn't prompt twice.
 9. On Linux, installs `etc/profile.d/disk-usage-warning.sh` to `/etc/profile.d/` (needs `sudo`) so each login warns when `/` or `/home` cross 85% usage.
@@ -107,7 +107,7 @@ The same `./install.sh` detects macOS and replaces `apt-get` with Homebrew. It f
 5. Deploys `bashrc-osx`, then appends one line to `~/.bash_profile` that sources `~/.bashrc`: macOS terminals open login shells, which never read `~/.bashrc` on their own. Done for both choices, so `bash` stays usable.
 6. Deploys `tmux.conf` to `~/.config/tmux/tmux.conf` (same step on Linux), clones [tpm](https://github.com/tmux-plugins/tpm) into `~/.config/tmux/plugins/tpm` and fetches the listed plugins headlessly (resurrect + continuum restore your sessions, window-name renames windows after what runs in them). A `~/.tmux.conf` would be read instead, so one found is moved to `~/.tmux.conf.backup-<date>`; a differing `~/.config/tmux/tmux.conf` becomes `tmux.conf.backup-<date>`. `libtmux` (needed by window-name) goes in the python user site; brew's python blocks that by default, so the install retries with `--break-system-packages`. Both plugin steps only warn on failure: `prefix` + `I` inside tmux fetches the plugins. Prefix is `C-a`.
 7. **bash** chosen: makes brew's bash 5 the login shell (adds it to `/etc/shells` with `sudo`, then `chsh`, which asks for your password). macOS ships bash 3.2, too old for the bashrc.
-   **zsh** chosen: installs oh-my-zsh with its official script (unattended, skipped if `~/.oh-my-zsh` exists), deploys `zsh/zshrc-osx` to `~/.zshrc` and the `bchanot` theme to `~/.oh-my-zsh/custom/themes/`, then makes `/bin/zsh` the login shell. An existing `~/.zshrc` that differs from the repo's is saved as `~/.zshrc.backup-<date>` (outside `~/Oldconfig`, which every run wipes). Move your machine-specific lines (nvm, bun, tokens) into `~/.zshrc.local`: the deployed zshrc loads it.
+   **zsh** chosen: installs oh-my-zsh with its official script (unattended, skipped if `~/.oh-my-zsh` exists), renders `zsh/zshrc-osx` into `~/.zshrc` (same identity as the bashrc) and deploys the `bchanot` theme to `~/.oh-my-zsh/custom/themes/`, then makes `/bin/zsh` the login shell. An existing `~/.zshrc` that differs from the repo's is saved as `~/.zshrc.backup-<date>` (outside `~/Oldconfig`, which every run wipes). Move your machine-specific lines (nvm, bun, tokens) into `~/.zshrc.local`: the deployed zshrc loads it.
 8. Ends with the list of what the Linux install has and this one does not: `gcc` (Apple clang answers to `gcc`), `valgrind`, `dkms`, `net-tools`, `openssh-server` and the RDP desktop (both built into macOS, switched on in System Settings > Sharing), `cifs-utils`, `php-imagick`, the NVIDIA driver, the disk-usage warning, `cloudpex`, the security baseline and the two end-of-install offers.
 
 ### CLI scripts (`bin/`)