docs(readme): better ASCII logo (ANSI Shadow)

[thegdsks]

Replace the primitive line-art logo with the ANSI Shadow style used by most modern terminal tools. Cleaner, bolder, renders consistently in GitHub markdown.

[github-actions]

Benchmark regression report

Threshold: 25%

goos: linux
goarch: amd64
pkg: github.com/glincker/theauth-go
cpu: AMD EPYC 9V74 80-Core Processor                
                     │ base-bench.txt │         pr-bench.txt          │
                     │     sec/op     │   sec/op     vs base          │
RateLimitReadHeavy-4      74.61n ± 7%   74.41n ± 1%  ~ (p=0.118 n=10)

                     │ base-bench.txt │          pr-bench.txt          │
                     │      B/op      │    B/op     vs base            │
RateLimitReadHeavy-4       0.000 ± 0%   0.000 ± 0%  ~ (p=1.000 n=10) ¹
¹ all samples are equal

                     │ base-bench.txt │          pr-bench.txt          │
                     │   allocs/op    │ allocs/op   vs base            │
RateLimitReadHeavy-4       0.000 ± 0%   0.000 ± 0%  ~ (p=1.000 n=10) ¹
¹ all samples are equal

pkg: github.com/glincker/theauth-go/crypto
               │ base-bench.txt │            pr-bench.txt            │
               │     sec/op     │   sec/op     vs base               │
Argon2Hash-4        51.28m ± 1%   51.23m ± 2%       ~ (p=1.000 n=10)
Argon2Verify-4      51.35m ± 1%   51.19m ± 1%       ~ (p=0.393 n=10)
geomean             51.31m        51.21m       -0.19%

               │ base-bench.txt │            pr-bench.txt             │
               │      B/op      │     B/op      vs base               │
Argon2Hash-4       64.01Mi ± 0%   64.01Mi ± 0%       ~ (p=0.089 n=10)
Argon2Verify-4     64.01Mi ± 0%   64.01Mi ± 0%       ~ (p=0.402 n=10)
geomean            64.01Mi        64.01Mi       +0.00%

               │ base-bench.txt │           pr-bench.txt            │
               │   allocs/op    │ allocs/op   vs base               │
Argon2Hash-4         102.0 ± 1%   102.0 ± 1%       ~ (p=0.487 n=10)
Argon2Verify-4       103.0 ± 1%   103.0 ± 0%       ~ (p=0.582 n=10)
geomean              102.5        102.5       +0.00%

pkg: github.com/glincker/theauth-go/internal/bench
                               │ base-bench.txt │            pr-bench.txt            │
                               │     sec/op     │   sec/op     vs base               │
AuditRedactor-4                     1.356µ ± 2%   1.367µ ± 1%  +0.81% (p=0.043 n=10)
OAuthCallback-4                     983.2n ± 0%   983.0n ± 1%       ~ (p=0.493 n=10)
OAuthCodeFlow-4                     49.92µ ± 1%   49.81µ ± 0%       ~ (p=0.579 n=10)
OAuthTokenEndpointRefreshHit-4      50.59µ ± 1%   50.31µ ± 1%       ~ (p=0.050 n=10)
JWKSEndpoint-4                      6.388µ ± 1%   6.395µ ± 1%       ~ (p=0.363 n=10)
SCIMTokenAuth-4                     16.01µ ± 1%   16.41µ ± 1%  +2.53% (p=0.000 n=10)
SessionLookup-4                     8.838µ ± 1%   8.842µ ± 2%       ~ (p=0.494 n=10)
geomean                             8.436µ        8.469µ       +0.38%

                               │ base-bench.txt │             pr-bench.txt              │
                               │      B/op      │     B/op      vs base                 │
AuditRedactor-4                      672.0 ± 0%     672.0 ± 0%       ~ (p=1.000 n=10) ¹
OAuthCallback-4                    1.344Ki ± 0%   1.344Ki ± 0%       ~ (p=1.000 n=10) ¹
OAuthCodeFlow-4                    15.79Ki ± 0%   15.79Ki ± 0%       ~ (p=0.870 n=10)
OAuthTokenEndpointRefreshHit-4     15.55Ki ± 0%   15.54Ki ± 0%  -0.01% (p=0.018 n=10)
JWKSEndpoint-4                     2.963Ki ± 0%   2.963Ki ± 0%       ~ (p=1.000 n=10) ¹
SCIMTokenAuth-4                    9.765Ki ± 0%   9.765Ki ± 0%       ~ (p=1.000 n=10)
SessionLookup-4                    8.452Ki ± 0%   8.451Ki ± 0%  -0.01% (p=0.033 n=10)
geomean                            4.729Ki        4.729Ki       -0.00%
¹ all samples are equal

                               │ base-bench.txt │            pr-bench.txt             │
                               │   allocs/op    │ allocs/op   vs base                 │
AuditRedactor-4                      4.000 ± 0%   4.000 ± 0%       ~ (p=1.000 n=10) ¹
OAuthCallback-4                      5.000 ± 0%   5.000 ± 0%       ~ (p=1.000 n=10) ¹
OAuthCodeFlow-4                      100.0 ± 0%   100.0 ± 0%       ~ (p=1.000 n=10) ¹
OAuthTokenEndpointRefreshHit-4       100.0 ± 0%   100.0 ± 0%       ~ (p=1.000 n=10) ¹
JWKSEndpoint-4                       37.00 ± 0%   37.00 ± 0%       ~ (p=1.000 n=10) ¹
SCIMTokenAuth-4                      56.00 ± 0%   56.00 ± 0%       ~ (p=1.000 n=10) ¹
SessionLookup-4                      42.00 ± 0%   42.00 ± 0%       ~ (p=1.000 n=10) ¹
geomean                              29.04        29.04       +0.00%
¹ all samples are equal

pkg: github.com/glincker/theauth-go/internal/jwt
            │ base-bench.txt │            pr-bench.txt            │
            │     sec/op     │   sec/op     vs base               │
JWTSign-4        33.28µ ± 1%   33.33µ ± 0%       ~ (p=0.353 n=10)
JWTVerify-4      77.68µ ± 0%   77.82µ ± 1%       ~ (p=0.393 n=10)
geomean          50.85µ        50.93µ       +0.16%

            │ base-bench.txt │             pr-bench.txt              │
            │      B/op      │     B/op      vs base                 │
JWTSign-4       2.782Ki ± 0%   2.782Ki ± 0%       ~ (p=1.000 n=10) ¹
JWTVerify-4     3.422Ki ± 0%   3.422Ki ± 0%       ~ (p=1.000 n=10) ¹
geomean         3.086Ki        3.086Ki       +0.00%
¹ all samples are equal

            │ base-bench.txt │            pr-bench.txt             │
            │   allocs/op    │ allocs/op   vs base                 │
JWTSign-4         15.00 ± 0%   15.00 ± 0%       ~ (p=1.000 n=10) ¹
JWTVerify-4       61.00 ± 0%   61.00 ± 0%       ~ (p=1.000 n=10) ¹
geomean           30.25        30.25       +0.00%
¹ all samples are equal

Generated by the bench workflow. A + delta means the PR branch is slower.