fix(yew-link): surface initial internal fetch errors instead of retrying indefinitely

[cuishuang]

Description

Fix the client-side use_linked_state retry loop caused by initial LinkError::Internal results not being cached.

Initial fetches now cache all completed results, including infrastructure errors. This allows the suspension to resolve and exposes the error through LinkedStateHandle::as_result() instead of creating another identical request.

Refresh behavior remains unchanged: LinkError::Internal results from background refreshes are not cached, so an existing stale value is preserved.

Fixes #4218

Checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Visit the preview URL for this PR (updated for commit 80cd486):

https://yew-rs-api--pr4219-master-68tx4rnl.web.app

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[github-actions]

Size Comparison

Details

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	100.206	100.206	0	0.000%
boids	164.938	164.938	0	0.000%
communication_child_to_parent	93.710	93.710	0	0.000%
communication_grandchild_with_grandparent	105.993	105.993	0	0.000%
communication_grandparent_to_grandchild	102.314	102.314	0	0.000%
communication_parent_to_child	91.101	91.101	0	0.000%
contexts	106.300	106.300	0	0.000%
counter	86.271	86.271	0	0.000%
counter_functional	88.302	88.302	0	0.000%
dyn_create_destroy_apps	90.170	90.170	0	0.000%
file_upload	98.577	98.577	0	0.000%
function_delayed_input	94.617	94.617	0	0.000%
function_memory_game	168.581	168.581	0	0.000%
function_router	400.298	400.298	0	0.000%
function_todomvc	164.981	164.981	0	0.000%
futures	235.946	235.946	0	0.000%
game_of_life	100.623	100.623	0	0.000%
immutable	258.612	258.612	0	0.000%
inner_html	80.781	80.781	0	0.000%
js_callback	109.758	109.758	0	0.000%
keyed_list	176.339	176.339	0	0.000%
mount_point	84.192	84.192	0	0.000%
nested_list	112.731	112.731	0	0.000%
node_refs	91.776	91.776	0	0.000%
password_strength	1765.649	1765.649	0	0.000%
portals	93.599	93.599	0	0.000%
router	366.529	366.529	0	0.000%
suspense	113.938	113.938	0	0.000%
timer	88.518	88.518	0	0.000%
timer_functional	99.423	99.423	0	0.000%
todomvc	141.977	141.977	0	0.000%
two_apps	86.176	86.176	0	0.000%
web_worker_fib	136.490	136.490	0	0.000%
web_worker_prime	186.573	186.573	0	0.000%
webgl	82.927	82.927	0	0.000%

✅ None of the examples has changed their size significantly.