fix(parsers): harden RPC/price/updater parsing against valid-but-unhandled input

Audit of the full-node RPC response parsers and updater release-body parsers
(find -> adversarially-verify workflow) surfaced three worth fixing; three
others guard formats the project doesn't emit and are backstopped by signature
verification, so they're documented rather than churned.

- Price (Medium): parseCoinGeckoPriceResponse used .value(key, 0.0), which
  throws type_error on a PRESENT null. CoinGecko emits null for usd_24h_change/
  usd_24h_vol on illiquid tokens (DRGX is one) while still returning a valid
  spot price; the outer catch turned that into no price update at all. Read
  null-tolerantly so the valid usd/btc survives.

- Daemon updater (Medium): parseDaemonChecksums blanked '|'/backtick but not
  markdown emphasis, so a bolded **archive.zip** checksum row was dropped and a
  valid, correctly-signed release would be refused. Also blank '*'/'_' (cannot
  cause a wrong-asset match; the 64-hex + .zip-suffix tests are unchanged).

- Opid poll (Low, severe failure mode): parseOperationStatusPoll read id/status
  via .value() (throws on a present non-string) and the call site parsed OUTSIDE
  its try/catch, so a throw left opid_poll_in_progress_ stuck true and wedged all
  z-operation polling for the session. Type-check the reads and parse inside the
  guard. (dragonxd can't emit non-string id/status; this is defense-in-depth.)

Regression tests: CoinGecko null field; opid non-string id/status; **bold**
checksum row. Suite green (1/1).

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

src/util/daemon_updater_core.cpp

@@ -140,15 +140,16 @@ std::map<std::string, std::string> parseDaemonChecksums(const std::string& body)
     //   | File | SHA-256 |
     //   |------|---------|
     //   | dragonx-1.0.2-linux-amd64.zip | `85f1dd…16` |
-    // Per line: blank out the table/code delimiters ('|' and '`'), then find the 64-hex token (the
-    // hash) and a token ending in ".zip" (the archive name). Header/separator/prose rows lack one
-    // or the other and are skipped, so this is robust to surrounding text and column order.
+    // Per line: blank out the table/code/emphasis delimiters ('|', '`', and markdown '*'/'_' so a
+    // bolded **archive.zip** still tokenizes), then find the 64-hex token (the hash) and a token
+    // ending in ".zip" (the archive name). Header/separator/prose rows lack one or the other and are
+    // skipped, so this is robust to surrounding text and column order.
     std::map<std::string, std::string> out;
     std::istringstream in(body);
     std::string line;
     while (std::getline(in, line)) {
         for (char& c : line)
-            if (c == '|' || c == '`') c = ' ';
+            if (c == '|' || c == '`' || c == '*' || c == '_') c = ' ';
         std::istringstream ls(line);
         std::string tok, hash, name;
         while (ls >> tok) {