feat(skills+terminal): make bundled skill scripts runnable out of the box (#13384)

* feat(skills): inject absolute skill dir and expand ${HERMES_SKILL_DIR} templates

When a skill loads, the activation message now exposes the absolute
skill directory and substitutes ${HERMES_SKILL_DIR} /
${HERMES_SESSION_ID} tokens in the SKILL.md body, so skills with
bundled scripts can instruct the agent to run them by absolute path
without an extra skill_view round-trip.

Also adds opt-in inline-shell expansion: !`cmd` snippets in SKILL.md
are pre-executed (with the skill directory as CWD) and their stdout is
inlined into the message before the agent reads it. Off by default —
enable via skills.inline_shell in config.yaml — because any snippet
runs on the host without approval.

Changes:
- agent/skill_commands.py: template substitution, inline-shell
  expansion, absolute skill-dir header, supporting-files list now
  shows both relative and absolute forms.
- hermes_cli/config.py: new skills.template_vars,
  skills.inline_shell, skills.inline_shell_timeout knobs.
- tests/agent/test_skill_commands.py: coverage for header, both
  template tokens (present and missing session id), template_vars
  disable, inline-shell default-off, enabled, CWD, and timeout.
- website/docs/developer-guide/creating-skills.md: documents the
  template tokens, the absolute-path header, and the opt-in inline
  shell with its security caveat.

Validation: tests/agent/ 1591 passed (includes 9 new tests).
E2E: loaded a real skill in an isolated HERMES_HOME; confirmed
${HERMES_SKILL_DIR} resolves to the absolute path, ${HERMES_SESSION_ID}
resolves to the passed task_id, !`date` runs when opt-in is set, and
stays literal when it isn't.

* feat(terminal): source ~/.bashrc (and user-listed init files) into session snapshot

bash login shells don't source ~/.bashrc, so tools that install themselves
there — nvm, asdf, pyenv, cargo, custom PATH exports — stay invisible to
the environment snapshot Hermes builds once per session.  Under systemd
or any context with a minimal parent env, that surfaces as
'node: command not found' in the terminal tool even though the binary
is reachable from every interactive shell on the machine.

Changes:
- tools/environments/local.py: before the login-shell snapshot bootstrap
  runs, prepend guarded 'source <file>' lines for each resolved init
  file.  Missing files are skipped, each source is wrapped with a
  '[ -r ... ] && . ... || true' guard so a broken rc can't abort the
  bootstrap.
- hermes_cli/config.py: new terminal.shell_init_files (explicit list,
  supports ~ and ${VAR}) and terminal.auto_source_bashrc (default on)
  knobs.  When shell_init_files is set it takes precedence; when it's
  empty and auto_source_bashrc is on, ~/.bashrc gets auto-sourced.
- tests/tools/test_local_shell_init.py: 10 tests covering the resolver
  (auto-bashrc, missing file, explicit override, ~/${VAR} expansion,
  opt-out) and the prelude builder (quoting, guarded sourcing), plus
  a real-LocalEnvironment snapshot test that confirms exports in the
  init file land in subsequent commands' environment.
- website/docs/reference/faq.md: documents the fix in Troubleshooting,
  including the zsh-user pattern of sourcing ~/.zshrc or nvm.sh
  directly via shell_init_files.

Validation: 10/10 new tests pass; tests/tools/test_local_*.py 40/40
pass; tests/agent/ 1591/1591 pass; tests/hermes_cli/test_config.py
50/50 pass.  E2E in an isolated HERMES_HOME: confirmed that a fake
~/.bashrc setting a marker var and PATH addition shows up in a real
LocalEnvironment().execute() call, that auto_source_bashrc=false
suppresses it, that an explicit shell_init_files entry wins over the
auto default, and that a missing bashrc is silently skipped.

website/docs/reference/faq.md

@@ -160,6 +160,33 @@ brew install python@3.12      # macOS
 
 The installer handles this automatically — if you see this error during manual installation, upgrade Python first.
 
+#### Terminal commands say `node: command not found` (or `nvm`, `pyenv`, `asdf`, …)
+
+**Cause:** Hermes builds a per-session environment snapshot by running `bash -l` once at startup. A bash login shell reads `/etc/profile`, `~/.bash_profile`, and `~/.profile`, but **does not source `~/.bashrc`** — so tools that install themselves there (`nvm`, `asdf`, `pyenv`, `cargo`, custom `PATH` exports) stay invisible to the snapshot. This most commonly happens when Hermes runs under systemd or in a minimal shell where nothing has pre-loaded the interactive shell profile.
+
+**Solution:** Hermes auto-sources `~/.bashrc` by default. If that's not enough — e.g. you're a zsh user whose PATH lives in `~/.zshrc`, or you init `nvm` from a standalone file — list the extra files to source in `~/.hermes/config.yaml`:
+
+```yaml
+terminal:
+  shell_init_files:
+    - ~/.zshrc                     # zsh users: pulls zsh-managed PATH into the bash snapshot
+    - ~/.nvm/nvm.sh                # direct nvm init (works regardless of shell)
+    - /etc/profile.d/cargo.sh      # system-wide rc files
+  # When this list is set, the default ~/.bashrc auto-source is NOT added —
+  # include it explicitly if you want both:
+  #   - ~/.bashrc
+  #   - ~/.zshrc
+```
+
+Missing files are skipped silently. Sourcing happens in bash, so files that rely on zsh-only syntax may error — if that's a concern, source just the PATH-setting portion (e.g. nvm's `nvm.sh` directly) rather than the whole rc file.
+
+To disable the auto-source behaviour (strict login-shell semantics only):
+
+```yaml
+terminal:
+  auto_source_bashrc: false
+```
+
 #### `uv: command not found`
 
 **Cause:** The `uv` package manager isn't installed or not in PATH.