dialogs: migrate to wxSizerFlags, retire wxDesigner, eliminate GCC 15 enum-enum conversion warnings - #473

…mule-project#466) (amule-project#473)

The Shared Files view could only show static counters (transferred,
requests, accepts, complete sources) — unlike Downloads, there was no way
to tell an actively-seeded file from an idle one. Surface per-file upload
activity over EC so clients (the REST API now, the desktop GUI later) can
add the corresponding columns.

Core (CKnownFile):
  * GetUploadDatarate() / GetTransferringClientCount() — live, summed from
    m_ClientUploadList: current upload speed and peers uploading now.
  * m_lastUploadDatetime — stamped in CFileStatistic::AddTransferred (the
    single point where sent bytes are attributed to a file), the upload-side
    analogue of the download's m_lastDateChanged.
  * m_dateShared — stamped once when a file completes (CompleteFileEnded) or
    is first hashed into the share (CKnownFileList::Append, afterHashing).
  Both persist in known.met as new FT_ tags (FT_LASTUPLOADED / FT_SHAREDSINCE);
  absent on a pre-feature known.met => 0 (unknown). Uploading never rewrites
  the shared file, so the timestamp can't ride the .met date the way downloads
  do — it needs its own tag. The unknown-tag preserve-and-rewrite path keeps
  this forward/backward compatible.

EC / dirty-marking:
  * New tags EC_TAG_KNOWNFILE_UPLOAD_SPEED / _UPLOADING_COUNT / _LAST_UPLOAD
    (live, emitted before the UPDATE early-return) and _SHARED_SINCE (full
    detail).
  * SetUploadState marks the file EC-dirty on US_UPLOADING transitions so a
    file that stops uploading but stays queued drops its speed to 0 —
    completed/shared files have no per-tick Process() sweep like downloads.

REST + SSE (amuleapi):
  * /shared list + detail gain upload_speed_bps, uploading, last_upload,
    shared_since; the SSE shared_added/shared_updated payload and EqualShared
    comparator carry them so live changes emit events.

Tests: RefresherTest decodes the new tags; curl 04 asserts the fields.
Docs: docs/api/REFERENCE.md.

…ct#675) (amule-project#744)

This is a deliberate UI change, not a behaviour-preserving refactor --
worth being explicit about per review discussion on amule-project#675. None of the
74 sites touched here have ever rendered their border: the legacy
`Add(window, proportion, flag, border)` form only applies `border`
when `flag` carries a direction bit (wxALL/wxLEFT/wxRIGHT/wxTOP/
wxBOTTOM), and all 74 omitted it. Converting to wxSizerFlags() and
supplying a real direction bit means these borders render for the
first time, which will reflow the affected dialogs to some degree.

Per amule-project#663 (the case that originally surfaced this pattern): the
recorded border values were never validated by anything, since they
never rendered. Each site was judged against its structural siblings
rather than ported verbatim -- where siblings already carried a
working border, matched to it; where a site was the outlier in an
otherwise-consistent row/grid, adjusted to match rather than
introducing a new, never-tested value. A few sites lost their border
entirely where every sibling in the same row already had none (the
stray value read as leftover noise, not an intended margin).

Three additional non-legacy-syntax inconsistencies folded into the
same pass (found while scoping amule-project#675, confirmed still present):
- PreferencesRemoteControlsTab: "Low rights password" carried
  Border(wxLEFT|wxRIGHT, 20) while every other same-column label in
  the grid ("Web template", "Full rights password") uses
  Border(wxRIGHT, 5) -- the 20px left indent looked like it was
  copy-pasted from the unrelated UPnP-port row's indent, not a
  deliberate choice for this row.
- PreferencesOnlineSigTab: the "Save online signature file in" path
  field had no Expand()/proportion despite sitting in a column its
  parent FlexGridSizer marks growable -- it couldn't actually grow to
  fill the space reserved for it.
- PreferencesGeneralTab: the "Browser Selection" row (text field +
  Browse button) still used the legacy 3-arg Add() form while the
  structurally identical "Video Player" row already used
  wxSizerFlags() -- modernized for consistency, no behaviour change
  (both used border 0).

Scope: src/muuli_wdr.cpp only, matching where amule-project#663/amule-project#473 originally
established (and didn't fully carry through) the wxSizerFlags()
convention.

Testing: full build verified (macOS). Visually walked every dialog
these 20 functions produce that's reachable without live server/
download/client data in a fresh test config: main status bar,
search, transfer panes, shared-files header, servers/Kad tabs,
Friends/Messages panels, and all 15 Preferences tabs -- no clipped or
overlapping controls, and the two directly-testable fixes (the
OnlineSig path field now expanding, the RemoteControls password grid
column now aligned) confirmed visually.

NOT independently verified: fileDetails, clientDetails, commentLstDlg,
and CategoriesEditWindow all require live downloads/shared files/
clients/categories to reach via the UI, which a from-scratch test
config doesn't have -- these got the same siblings-based border
review as everything else, but I have not seen them rendered.
Sizer-border rendering is exactly where wxGTK/wxMSW/wxOSX diverge, so
this needs eyes on Linux and Windows too, per the amule-project#675 review
discussion.