webui: use date in more human readable exported filename (#19939)

* webui: use date in exported filename

Move conversation naming and export to utils

update index.html.gz

* webui: move literals to message export constants file

* webui: move export naming and download back to the conversation store

* chore: update webui build output

* webui: add comments to some constants

* chore: update webui build output

tools/server/webui/src/lib/constants/message-export.ts

@@ -0,0 +1,20 @@
+// Conversation filename constants
+
+// Length of the trimmed conversation ID in the filename
+export const EXPORT_CONV_ID_TRIM_LENGTH = 8;
+// Maximum length of the sanitized conversation name snippet
+export const EXPORT_CONV_NAME_SUFFIX_MAX_LENGTH = 20;
+// Characters to keep in the ISO timestamp. 19 keeps 2026-01-01T00:00:00
+export const ISO_TIMESTAMP_SLICE_LENGTH = 19;
+
+// Replacements for making the conversation title filename-friendly
+export const NON_ALPHANUMERIC_REGEX = /[^a-z0-9]/gi;
+export const EXPORT_CONV_NONALNUM_REPLACEMENT = '_';
+export const MULTIPLE_UNDERSCORE_REGEX = /_+/g;
+
+// Replacements to the ISO date for use in the export filename
+export const ISO_DATE_TIME_SEPARATOR = 'T';
+export const ISO_DATE_TIME_SEPARATOR_REPLACEMENT = '_';
+
+export const ISO_TIME_SEPARATOR = ':';
+export const ISO_TIME_SEPARATOR_REPLACEMENT = '-';