fix(extension): show Add-to-FC button on subscribed Patreon creators (#1485)

Symptom (operator-flagged): the extension injected the Add-as-source button on
a Patreon creator you had NOT subscribed to, but it disappeared once you were
subscribed — the opposite of when it's useful.

Root cause (extension logic, not Patreon security): Patreon serves a creator
under three URL shapes — bare patreon.com/Atole, patreon.com/c/Atole, and
patreon.com/cw/Atole (the 'creator workspace' URL you land on once subscribed;
documented in patreon_resolver._VANITY_RE). The button's artist-page gate
(PLATFORM_ARTIST_PATTERNS.patreon in platforms.js) and its byte-mirror probe
pattern (_PLATFORM_PATTERNS in extension_service._derive) only matched the bare
single-segment form and explicitly excluded c/. So the subscribed-view URL
failed the gate → no button. The ingestion resolver already handled all three;
only these two gates were too narrow.

Fix: both regexes now accept optional cw/ and c/ prefixes and drop the strict
single-segment end-anchor, so a creator's inner page (/cw/Atole/posts,
/Atole/membership) also matches — robust to whatever exact shape the subscribed
view uses. Nav-page exclusions (home/search/messages/notifications/library/
settings/posts + post permalinks) preserved. New unit test covers all three
prefixes, sub-paths, and nav-page rejection (both regexes validated identically).

Bump extension 1.0.7→1.0.8 so a fresh signed XPI ships the fix (also exercises
batch-5 web-ext-10's AMO sign path end-to-end on the main build).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

extension/package.json

@@ -1,6 +1,6 @@
 {
   "name": "fabledcurator-extension",
-  "version": "1.0.7",
+  "version": "1.0.8",
   "private": true,
   "description": "Firefox extension for FabledCurator",
   "scripts": {