feat(files): preview text files from outside the workspace, and stop routing them at a viewer that cannot read them

A .json/.log/.yaml/code path outside the session workspace was refused as an
unsupported type, and clicking one in the terminal made it worse: text goes to
the log viewer, which spawns `tail -f` and allows only the workspace, /var/log
and ~/logs, so it answered "Path must be within working directory or allowed
log directories" while the same path clicked in the response viewer previewed
fine. Two surfaces, two answers, for a file the session can already cat.

- TEXT_ATTACHMENT_EXTENSIONS IS EDITABLE_EXTENSIONS (config/file-editing.ts),
  not a second curated list that would drift from it. The rule reads: if the
  viewer would open a file for editing inside the workspace, the same file
  outside it can be read. The suffix was never the confidentiality gate here,
  the path guard is (sensitive-file blocklist, /root and /etc trees, realpath
  before the check), and it still runs on every registration.
- Widening what can be READ must not widen what can RUN. html/htm join svg in
  serveRawFile's download-only branch, so markup is never served with a
  renderable type on our own origin; other text goes out as inert
  text/plain; charset=utf-8 with nosniff, matching what the path picker does.
  The preview reads through fetch(), which ignores the disposition, so a
  clicked .html still shows its source.
- ~/.codeman*/state.json joins isSensitivePath. It persists
  SessionState.envOverrides and the env allowlist admits key-shaped names
  (GEMINI_API_KEY, CLAUDE_CODE_*), so it can hold a live credential. Same
  treatment as hook-secret and users.json, and the rest of the tree stays
  attachable.
- The terminal sends an out-of-workspace path to the preview instead of the log
  viewer. In-workspace text keeps the tail viewer, which is the point of it, and
  file-stream-manager's allowlist is untouched: no `tail -f` on arbitrary host
  paths.
- The by-id text preview is bounded like the workspace one: a Range request for
  the first 512KB (a real partial read, not a discarded 50MB download) plus a
  500-line cap, with the footer saying so.

Verified on an isolated instance: a 1.1MB external log opens in ~1.8s showing
500 lines with "showing first 500 lines" in the footer; json, yaml and code
preview; an .html carrying a script tag renders as source and does not execute;
.svg is still refused; a terminal click on an external .yaml opens the preview
with no log viewer and no attachment card; an in-workspace .log still opens the
streaming tail viewer.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

test/sensitive-path.test.ts

@@ -73,6 +73,12 @@ describe('isSensitivePath', () => {
       ['codeman hook secret', `${HOME}/.codeman/hook-secret`],
       ['codeman user table', `${HOME}/.codeman/users.json`],
       ['codeman hook secret on a named instance', `${HOME}/.codeman-beta/hook-secret`],
+      // state.json persists SessionState.envOverrides, and the env allowlist
+      // admits key-shaped names (GEMINI_API_KEY, CLAUDE_CODE_*), so it can hold
+      // a live credential. Named once .json became previewable from outside the
+      // workspace.
+      ['codeman state file', `${HOME}/.codeman/state.json`],
+      ['codeman state file on a named instance', `${HOME}/.codeman-beta/state.json`],
     ];
 
     it.each(blocked)('blocks the %s', (_label, path) => {
@@ -88,6 +94,7 @@ describe('isSensitivePath', () => {
       // The publish skill and the review-card loop attach from these trees, so
       // only their named secret members are blocked, never the whole tree.
       ['a codeman screenshot', `${HOME}/.codeman/screenshots/shot.png`],
+      ['a codeman lifecycle log', `${HOME}/.codeman/session-lifecycle.jsonl`],
       ['a claude transcript', `${HOME}/.claude/projects/proj/session.jsonl`],
       ['a claude team inbox', `${HOME}/.claude/teams/alpha/inboxes/bob.json`],
       // isUnderTree-style separator awareness: a sibling name that merely starts