refactor: generalize DSML tag parsing to tolerate model noise; split tiktoken by build tags

Replace hardcoded DSML typo variant lists in Go/Node tool call parsers with
generalized prefix consumption that tolerates repeated leading <, repeated DSML
prefix noise, and trailing pipe terminators. Split tiktoken-dependent token
counting into a build-tagged file for non-cgo platform compatibility. Add /data
directory to Dockerfile for bind-mount permissions.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/deepseek/protocol/constants_shared.json

@@ -2,7 +2,7 @@
   "client": {
     "name": "DeepSeek",
     "platform": "android",
-    "version": "2.0.3",
+    "version": "2.0.4",
     "android_api_level": "35",
     "locale": "zh_CN"
   },
@@ -24,4 +24,4 @@
   "skip_exact_paths": [
     "response/search_status"
   ]
-}
+}