fix: v0.5.0 security and robustness fixes from the 2026-10-07 review

- Ask Claude: strip control characters, send as bracketed paste (closes #2)
- end: forget before kill, so ending from inside a session leaves no ghost (closes #3)
- reconnects use `attach --existing` and never resurrect ended/renamed sessions (closes #4)
- repo: git --no-optional-locks, no safe.directory override, refresh on connect/bell/60s (closes #5)
- uploads: unique names via mktemp, cleanup trap on hangup (closes #6)
- clipboard: write-only OSC 52 provider, tmux allow-passthrough off (closes #7)
- uploads: size check up front, streamed slices, idle timeout (closes #9)
- --list: path last in TSV rows, tolerant numbers (closes #10)
- tokens via curl config on stdin; userinfo stripped from remote URLs (closes #11)
- ttyd max clients 32 and at most 2 concurrent side-channel calls (#8; BroadcastChannel polling still open)
- tmux: fixed terminal-features index (no duplicates on re-source), no status-right clock

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libexec/devdesk-serve

@@ -13,7 +13,7 @@ args=(
     --writable                          # ttyd >= 1.7.4 is read-only by default
     --url-arg                           # ?arg=<session> becomes `devdesk attach <session>`
     --check-origin                      # refuse cross-site WebSocket connections
-    --max-clients "${DEVDESK_MAX_CLIENTS:-8}"
+    --max-clients "${DEVDESK_MAX_CLIENTS:-32}"
     --credential "$DEVDESK_CREDENTIAL"  # injected by NPM as an Authorization header
     --index "${DEVDESK_INDEX:-/usr/share/devdesk/index.html}"
     --debug "${DEVDESK_TTYD_LOG_LEVEL:-3}" # errors+warnings only: notice level would log the credential