fix(ec): reject EC tags whose declared length underflows the children size - #879

…ule-project#912)

Extends existing categories (preferring extensions over new lines):
- Performance/Upload: amule-project#898 SlotAllocation default raised.
- Networking & Discovery: wire-parser hardening list extended with
  amule-project#879/amule-project#882/amule-project#890/amule-project#886; new amuleweb security hardening bullet
  consolidating ngosang's amule-project#869-amule-project#874 triage (all landed in amule-project#875);
  amulegui list extended with amule-project#857; shared-folder watcher extended
  with amule-project#858.
- Packaging: Windows installer i18n line extended with amule-project#899.
- Internals & Refactoring: new docs-polish + code-quality bullets
  covering amule-project#851/amule-project#855/amule-project#862/amule-project#888/amule-project#900/amule-project#866/amule-project#867/amule-project#895 and amule-project#909/amule-project#910/amule-project#912.
- Translations: new pre-release final-wave bullet covering amule-project#847/amule-project#856/
  amule-project#891/amule-project#908/amule-project#860/amule-project#904/amule-project#859/amule-project#863/amule-project#861/amule-project#880/amule-project#911/amule-project#901/amule-project#902/amule-project#889/amule-project#868/amule-project#853.
- Bug Fixes & Stability: amule-project#850/amule-project#854/amule-project#878/amule-project#906.
- CI: ccache wiring (amule-project#892, amule-project#903) + CodeQL binutils-dev (amule-project#907).

Contributors footer gains mifritscher and nguyenhoangminhhieu2004-gif
(both first-time contributors).

PR index extended through amule-project#912.

Extends existing categories (preferring extensions over new lines):
- Performance/Upload: #898 SlotAllocation default raised.
- Networking & Discovery: wire-parser hardening list extended with
  #879/#882/#890/#886; new amuleweb security hardening bullet
  consolidating ngosang's #869-#874 triage (all landed in #875);
  amulegui list extended with #857; shared-folder watcher extended
  with #858.
- Packaging: Windows installer i18n line extended with #899.
- Internals & Refactoring: new docs-polish + code-quality bullets
  covering #851/#855/#862/#888/#900/#866/#867/#895 and #909/#910/#912.
- Translations: new pre-release final-wave bullet covering #847/#856/
  #891/#908/#860/#904/#859/#863/#861/#880/#911/#901/#902/#889/#868/#853.
- Bug Fixes & Stability: #850/#854/#878/#906.
- CI: ccache wiring (#892, #903) + CodeQL binutils-dev (#907).

Contributors footer gains mifritscher and nguyenhoangminhhieu2004-gif
(both first-time contributors).

PR index extended through #912.

…mule-project#879)

CECTag's double constructor serialises through a default ostringstream,
whose precision is 6 significant digits. That is fine for the small
magnitudes most double tags carry (rates, ratios), but the statsgraph
timestamp is seconds of uptime, and once it passes 1e6 the stream
switches to scientific notation and quantises the value: a 10-second
grid after ~11.6 days of uptime, 100 seconds after ~115 days.

The statistics graph uses that timestamp as a delta marker. The client
stores the newest point's timestamp and sends it back as
EC_TAG_STATSGRAPH_LAST; the core returns everything newer. Quantised in
both directions, the marker is wrong by up to a full grid step, so the
core either resends points the client already has or skips points it
never sent -- duplicated or missing samples on every refresh, on any
daemon up more than ~11.6 days.

Serialise with max_digits10 instead, the shortest precision that
round-trips a double exactly. The tag stays a length-prefixed
NUL-terminated string, so the longer text is compatible in both
directions; GetDoubleData() parses it with istringstream unchanged.