Blips aren't handled correctly every time, resulting in a lot of 404
URLs and invalid blips.

Sometimes, WebP icons won't load despite extensions.json clearly
defining it as the only extension used for all image data.

I suspect there's a race condition between fetching extensions.json,
parsing it into client, and checking what extension we should use to get
character icons during loading. Sometimes it correctly loads images,
sometimes it falls back and starts requesting PNG instead.

I couldn't precisely identify where it happens and what's the root
cause. As a workaround, this commit instead makes WebP the
first-priority extension and a fallback.

For whatever reason, WebAO decides to normalize almost every string
component in URLs, packets, and INI files to lower case.

First, the glaring issue. In the URLs, this handling of paths is utterly
broken and corrupts data. By mangling characters, you change the
resource identity and break valid URLs. According to section 6.2.2.1 of
RFC 3986 (Case Normalization):

> When a URI uses components of the generic syntax, the component syntax
> equivalence rules always apply; namely, that the scheme and host are
> case-insensitive and therefore should be normalized to lowercase. For
> example, the URI <HTTP://www.EXAMPLE.com/> is equivalent to
> <http://www.example.com/>. The other generic syntax components are
> assumed to be case-sensitive unless specifically defined otherwise by
> the scheme (see Section 6.2.3)

Scheme and host _are_ case-insensitive. Path is _not_, so isn't
everything else. Section 6.2.3 doesn't define any normalization for the
path component in HTTP schemes. Thus, example.com/item and
example.com/Item are two different resources.

I can only think of idiotic conventions of a particular poorly designed
file system when it comes to this absurdity. There's no reason to drag
them around in our developments. For these systems, case doesn't matter
anyway, normalization is their job, not server hosts' who end up having
to either rewrite every URL request for every asset, or mangle their
asset directory and then rewrite almost every INI config (and spam
"showname=Name" everywhere because now your character directory has to
be "name").

So, instead of using absurd ad-hoc solutions to a broken implementation
such as forcing everything to lower case on the server side, this commit
attempts to fix the root issue and make URL handling conformant to
relevant standards.

Similar situation with strings within packets, although not as severe
in practice. Case must be preserved, otherwise it's corrupting data for
no reason. If a normalization is needed, it should be done at the call
site of whatever requires it (like a filtering function), not by the
parser.

As for the INI, it's opinionated. While the values absolutely must not
be normalized, a case can be made for keys and section names: why not
allow "Options", "options", or even "oPtiOnS"? It's more convenient, and
corresponds to the platform quirk of Windows (which Qt unfortunately
inherits in AO2 Client). I don't think there's a good reason to allow
such leniency in parsing, and removing superfluous normalization is a
better move: less data transformations, less ambiguity, more strictness.
In practice, INIs tend to be well-formed, and it's good discipline to
write them this way.

In several places, the case-folding does make sense: callwords,
OOC commands, CSS class names for areas, and character list filters.
These will behave weirdly and inconveniently without it. In most places,
however, it only causes unnecessary breakage.

Instead of hardcoding .png, read the preferred extension from
client.charicon_extensions[0] (populated via extensions.json),
falling back to .png if unavailable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Instead of eagerly fetching char_icon (with HEAD requests per extension)
and char.ini for every character on join, set img.src directly to
char_icon.png and defer char.ini loading until actually needed (character
selection via handlePV, or first IC message via handleMS). This
eliminates thousands of HTTP requests on join for large character lists.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>