Multiple related bugs in the Save-to-Flash path:
1. Multipart upload was missing the required filename argument,
causing the backend parser to fail. Added 'config.txt' to the
form.append call. This was likely the primary reason Save-to-Flash
was unreliable.
2. Web UI was not pausing its polling interval during flash write,
causing CPU contention and intermittent crashes. Added isSaving
lock and clearInterval before sendConfig.
3. conf_cmds whitelist was incomplete. Added: syslog, passwd, pvid,
ingress, port name, lag, laghash, isolate, stp, igmp, mtu, bw,
vlan N mgmt, vlan N d.
4. VLAN regex blocked named VLANs. New pattern allows optional name
(starts with letter, matching CLI parser semantics).
5. vlan N d (delete) was not persisted. parseConf now removes the
matching vlan N ... entry from configuration[] when seeing a
delete command, without storing the delete itself. Result: the
saved config describes the end state.
6. configuration[] was not cleared between flashSave invocations,
leading to stale entries from prior interactions.
7. conf_overwrite boundary fix: 'pvid 1' no longer matches 'pvid 10'
etc. Added trailing space in startsWith check.
8. All conf_cmds patterns now anchored with ^...$ for full-line
match. parseConf normalizes whitespace before testing.
9. Port range widened to \d{1,2} so ports 11+ are accepted.
Structural fixes (1, 2, 6, 7, 8) ported from mcaptur's closed PR #219;
remaining fixes (3, 4, 5, 9) and overall regex strategy are new.