Add JSON-LD and llms.txt for AI search

[halskiszymon]

Two SEO changes for the docs site. Nothing changes the rendered page.

• JSON-LD: Organization with the same @id as swmansion.com, plus SoftwareSourceCode for the library, derived from siteConfig. The identical @id is what makes engines read the docs and the company site as one entity instead of two unrelated ones.
• llms.txt, generated at build — no new dependency. Lists every docs page. The docs build now fails if the file is missing or lists nothing.

Both come from one local plugin, plugins/swm-geo.js, registered with a single line. The same change is going out across the docs repos; reference: software-mansion/react-native-reanimated#10332.

Check: CI prints llms.txt lists N pages.

[github-actions]

WPT non-regression comparison

PASS — no regressions · 0 improved section(s) · overall 2632 → 2632 (0)

Unchanged sections (28)

Spec section	Base pass	Head pass	Delta
Processing model	0	0	0
Other	52	52	0
AnalyserNode	138	138	0
AudioBuffer	140	140	0
AudioBufferSourceNode	208	208	0
AudioContext	58	58	0
AudioNode	261	261	0
AudioParam	599	599	0
BiquadFilterNode	275	275	0
ChannelMergerNode	30	30	0
ChannelSplitterNode	7	7	0
ConstantSourceNode	59	59	0
ConvolverNode	170	170	0
DelayNode	104	104	0
DestinationNode	0	0	0
DynamicsCompressorNode	4	4	0
GainNode	15	15	0
IIRFilterNode	87	87	0
MediaElementAudioSourceNode	0	0	0
MediaStreamAudioDestinationNode	1	1	0
MediaStreamAudioSourceNode	0	0	0
OfflineAudioContext	35	35	0
OscillatorNode	104	104	0
PannerNode	75	75	0
PeriodicWave	33	33	0
ScriptProcessorNode	0	0	0
StereoPannerNode	102	102	0
WaveShaperNode	75	75	0

_{Baseline: 03d0debc941000cd07aed2da64ebe3bc8a759528 · Candidate: 9b05417d282951a6e99680c99b0e99b8817ec74d}

_{Workflow run · this comment is updated on every push.}