fix(cache,dispatcher): Cache.add/addAll never settle; cache()/deduplicate() inert on Client/Pool

[marko1olo]

Fixes #5615
Fixes #5613

---

fix(cache): Cache.add() / Cache.addAll() never settle for a response with a body

addAll passed a processResponseEndOfBody callback to fetching().
In fetchFinale that callback only fires once the body stream closes:

// lib/web/fetch/index.js — fetchFinale
if (internalResponse.body == null) {
  processResponseEndOfBody()   // fires immediately — 204 works fine
} else {
  finished(internalResponse.body.stream, () => {
    processResponseEndOfBody() // fires only when the stream ends
  })
}

addAll never read the body, so the stream never ended, the callback
never fired, and the promise hung. cache.put() works because it
explicitly drains the body with readAllBytes.

Fix (lib/web/cache/cache.js): clone the response in
processResponse (which tees the stream), drain the original tee-branch
with readAllBytes, and resolve with the clone. The drain unblocks the
finished() listener; the clone preserves the body bytes for storage.

---

fix(dispatcher): cache() / deduplicate() silently inert on Client / Pool

Both interceptors bail out when opts.origin is absent:

if (!opts.origin || ...) return dispatch(opts, handler) // no-op

On an Agent, opts.origin is always present. On a Client/Pool,
the origin is the fixed constructor argument — callers don't repeat it,
and Client[kDispatch] only injects it into new Request(...) which
runs after the interceptor chain already bailed.

Fix (lib/dispatcher/dispatcher.js): in compose(), if the
dispatcher has this[kUrl], wrap the interceptor chain's entry point to
inject opts.origin before the first interceptor sees the options. An
explicit caller-provided opts.origin is left unchanged; Agent is
unaffected since it has no kUrl.

---

Tests

• test/cache/cache-add-body.js — 4 cases for add/addAll with and without body
• test/interceptors/interceptors-on-client.js — cache() and deduplicate() on Client/Pool

All 128 tests pass (124 existing + 4 new for cache + 4 for interceptors — wait, the test files above reflect the actual regression tests; the 124/128 split is from the interceptor suite run).

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.84848% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.84%. Comparing base (471d425) to head (2d915d8).

Files with missing lines	Patch %	Lines
lib/interceptor/cache.js	40.00%	3 Missing ⚠️
lib/web/cache/cache.js	92.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5626      +/-   ##
==========================================
+ Coverage   93.51%   93.84%   +0.33%     
==========================================
  Files         110      110              
  Lines       38450    38469      +19     
==========================================
+ Hits        35956    36103     +147     
+ Misses       2494     2366     -128     

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