fix: add IntoPropValue impls for Cow<'static, str>

[Madoshakalaka]

Description

The dynamic tag name issue (<@{value} /> requiring Cow<'static, str>) was already resolved in #3431, which switched to Into<AttrValue>.

The remaining gap was that component props typed as Cow<'static, str> could not accept common string types directly in the html! macro. This PR adds the missing IntoPropValue implementations:

• &'static str to Cow<'static, str> (zero-cost via Cow::Borrowed)
• String to Cow<'static, str> (via Cow::Owned)
• Rc<str> to Cow<'static, str> (via Cow::Owned)

fixed now.

Fixes #3524

Checklist

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

[github-actions]

Benchmark - core

Yew Master

vnode           fastest       │ slowest       │ median        │ mean          │ samples │ iters
╰─ vnode_clone  2.125 ns      │ 2.231 ns      │ 2.128 ns      │ 2.131 ns      │ 100     │ 1000000000

Pull Request

vnode           fastest       │ slowest       │ median        │ mean          │ samples │ iters
╰─ vnode_clone  2.092 ns      │ 3.703 ns      │ 2.099 ns      │ 2.535 ns      │ 100     │ 1000000000

[github-actions]

Visit the preview URL for this PR (updated for commit 0561a55):

https://yew-rs-api--pr4051-fix-cow-into-prop-va-awrzc50h.web.app

_{(expires Fri, 13 Mar 2026 11:59:56 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

[github-actions]

Size Comparison

Details

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	100.272	100.272	0	0.000%
boids	168.099	168.099	0	0.000%
communication_child_to_parent	93.485	93.485	0	0.000%
communication_grandchild_with_grandparent	105.262	105.262	0	0.000%
communication_grandparent_to_grandchild	101.610	101.610	0	0.000%
communication_parent_to_child	90.899	90.899	0	0.000%
contexts	105.177	105.177	0	0.000%
counter	86.282	86.282	0	0.000%
counter_functional	88.276	88.276	0	0.000%
dyn_create_destroy_apps	90.322	90.322	0	0.000%
file_upload	99.377	99.377	0	0.000%
function_delayed_input	94.377	94.377	0	0.000%
function_memory_game	172.944	172.944	0	0.000%
function_router	406.599	406.599	0	0.000%
function_todomvc	164.163	164.163	0	0.000%
futures	235.191	235.191	0	0.000%
game_of_life	104.732	104.732	0	0.000%
immutable	255.891	255.891	0	0.000%
inner_html	80.803	80.803	0	0.000%
js_callback	109.401	109.401	0	0.000%
keyed_list	179.740	179.740	0	0.000%
mount_point	84.174	84.174	0	0.000%
nested_list	113.072	113.072	0	0.000%
node_refs	91.523	91.523	0	0.000%
password_strength	1729.185	1729.185	0	0.000%
portals	93.034	93.034	0	0.000%
router	377.158	377.158	0	0.000%
suspense	113.502	113.502	0	0.000%
timer	88.641	88.641	0	0.000%
timer_functional	98.881	98.881	0	0.000%
todomvc	142.114	142.114	0	0.000%
two_apps	86.176	86.176	0	0.000%
web_worker_fib	136.155	136.155	0	0.000%
web_worker_prime	187.383	187.383	0	0.000%
webgl	83.224	83.224	0	0.000%

✅ None of the examples has changed their size significantly.

[github-actions]

Benchmark - SSR

Yew Master

Details

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	310.684	311.020	310.819	0.132
Hello World	10	466.676	480.954	472.929	5.409
Function Router	10	32245.863	33595.617	32861.627	416.651
Concurrent Task	10	1006.600	1007.864	1007.351	0.433
Many Providers	10	1085.728	1123.979	1102.260	13.995

Pull Request

Details

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	310.582	312.502	311.132	0.543
Hello World	10	476.437	511.071	484.496	10.241
Function Router	10	34342.840	35310.333	34916.835	280.167
Concurrent Task	10	1005.740	1007.795	1006.875	0.677
Many Providers	10	1079.884	1105.710	1088.289	7.885

[Madoshakalaka]

the diagnostic diffs are all cosmetic