Co-authored-by: Peter McEvoy <git@mcevoypeter.com>

Reverts #827

This PR causes an instant segfault in the serf after upgrading on
`~dinleb-rambep`, `~norsyr-torryn` and probably all pre-existing ships.
The segfault has the following stacktrace:

```
urbit 3.4-0969b6de10
boot: home is /root/dinleb-rambep
disk: loaded epoch 0i575532513
loom: mapped 2048MB
boot: protected loom
live: mapped: GB/1.945.878.528
live: loaded: KB/16.384
boot: installed 1362 jets
loom: image backup complete
disk: created epoch 575532513
loom: mapped 2048MB
lite: arvo formula 4ce68411
lite: core 641296f
lite: final state 641296f
disk: loaded epoch 0i575532513
loom: mapped 2048MB
boot: protected loom
live: mapped: GB/1.945.878.528
live: loaded: KB/16.384
boot: installed 1362 jets
vere: checking version compatibility
loom: external fault: 0 (0x200000000 : 0x280000000)

Breakpoint 1, u3m_fault (adr_v=0x0, ser_i=<optimized out>) at pkg/noun/manage.c:1967
1967	pkg/noun/manage.c: No such file or directory.
(gdb) bt
#0  u3m_fault (adr_v=0x0, ser_i=<optimized out>) at pkg/noun/manage.c:1967
#1  0x00000000014b9544 in sigsegv_handler (sig=<optimized out>, sip=<optimized out>, ucp=0x1840b40 <Sigstk+6896>) at /home/runner/.cache/zig/p/N-V-__8AAHQhHwCCMyKUtQhO0AMsY182In-wQIwXVhenOql5/src/handler-unix.c:269
#2  <signal handler called>
#3  _n_burn (pog_u=0x1ffffe121ffffe5a, bus=<optimized out>, mov=1 '\001', off=-1 '\377') at pkg/noun/nock.c:2100
#4  0x0000000001273653 in _n_burn_out (bus=1950065936, pog_u=0x1fffffff4) at pkg/noun/nock.c:2814
#5  _n_burn_on (bus=1950065936, bus@entry=3460980861, fol=<optimized out>) at pkg/noun/nock.c:2837
#6  u3n_nock_on (bus=1950065936, bus@entry=3460980861, fol=<optimized out>) at pkg/noun/nock.c:2851
#7  0x0000000001271938 in u3v_poke_raw (sam=50403342) at pkg/noun/vortex.c:293
#8  u3v_poke (ovo=ovo@entry=3459182210) at pkg/noun/vortex.c:285
#9  0x0000000001262948 in u3m_soft_top (mil_w=mil_w@entry=0, pad_w=pad_w@entry=1048576, fun_f=0x12718d0 <u3v_poke>, arg=3459182210) at pkg/noun/manage.c:1311
#10 0x00000000012630ad in u3m_soft (mil_w=4294967284, mil_w@entry=0, fun_f=0x1d0ee947, arg=1950064560) at pkg/noun/manage.c:1577
#11 0x000000000161888d in _serf_poke (sef_u=<optimized out>, cap_c=<optimized out>, mil_w=0, job=job@entry=3455400141) at pkg/vere/serf.c:556
#12 0x0000000001617804 in _serf_work (sef_u=0x183ec20 <u3V>, mil_w=0, job=3455400141) at pkg/vere/serf.c:604
#13 u3_serf_work (sef_u=sef_u@entry=0x183ec20 <u3V>, mil_w=mil_w@entry=0, job=3455400141) at pkg/vere/serf.c:692
#14 0x0000000001618666 in u3_serf_writ (sef_u=0x183ec20 <u3V>, wit=3462698097, pel=pel@entry=0x7fffffff9a0c) at pkg/vere/serf.c:1160
#15 0x000000000126141d in _cw_serf_writ (vod_p=<optimized out>, len_d=113, byt_y=0x7ffff7ff8780 "\001\377\356Mn\235\001\b") at pkg/vere/main.c:1079
#16 0x00000000014ddf08 in _newt_meat_poke (mot_u=0x183ed90 <inn_u>, met_u=0x7ffff7ff8770) at pkg/vere/newt.c:62
#17 _newt_meat_next_sync (mot_u=0x183ed90 <inn_u>) at pkg/vere/newt.c:75
#18 _newt_read_sync_cb (str_u=0x183ed90 <inn_u>, len_i=<optimized out>, buf_u=<optimized out>) at pkg/vere/newt.c:236
#19 0x00000000014ccfe7 in uv__read (stream=0x183ed90 <inn_u>) at /home/runner/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/stream.c:1148
#20 uv__stream_io (loop=<optimized out>, w=0x183ee18 <inn_u+136>, events=1) at /home/runner/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/stream.c:1208
#21 0x00000000014c6b94 in uv__io_poll (loop=loop@entry=0x1864148 <default_loop_struct>, timeout=-1) at /home/runner/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/linux.c:1565
#22 0x00000000014c31f1 in uv_run (loop=loop@entry=0x1864148 <default_loop_struct>, mode=mode@entry=UV_RUN_DEFAULT) at /home/runner/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/core.c:460
#23 0x000000000125e791 in _cw_serf_commence (argc=<optimized out>, argv=<optimized out>) at pkg/vere/main.c:1299
#24 _cw_utils (argc=argc@entry=11, argv=argv@entry=0x7fffffffdf08) at pkg/vere/main.c:3250
#25 0x000000000125c7d9 in main (argc=11, argv=0x7fffffffdf08) at pkg/vere/main.c:3275
```

@quodss @joemfb

On develop, if a malformed scry URL is queried, we get a leak that ASAN
can detect. For example, after hitting F5 ten times at
`http://localhost:8080/_~_/=` and then pressing ctrl-D:

```
Direct leak of 240 byte(s) in 10 object(s) allocated from:
    #0 0x798dcccf6cbf in malloc (/usr/lib/clang/18/lib/linux/libclang_rt.asan-x86_64.so+0xf6cbf) (BuildId: 4cd39e6608b20f2f5a148a941cd434e0cadcd3dc)
    #1 0x1cd2706 in _http_req_dispatch /home/kirill/work/urbit-repos/vere/pkg/vere/io/http.c:983:29
    #2 0x1cd0dc6 in _http_rec_accept /home/kirill/work/urbit-repos/vere/pkg/vere/io/http.c:1676:7
    #3 0x1ce0378 in call_handlers /home/kirill/.cache/zig/p/N-V-__8AAJ2XqALM9jST2Gu4TIdjPNY2QB8rnmKeepeqr076/lib/core/request.c:155:13
    #4 0x1ea55ca in handle_incoming_request /home/kirill/.cache/zig/p/N-V-__8AAJ2XqALM9jST2Gu4TIdjPNY2QB8rnmKeepeqr076/lib/http1.c:470:13
    #5 0x1bdd68e in uv__read /home/kirill/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/stream.c:1148:7
    #6 0x1bdb3b7 in uv__stream_io /home/kirill/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/stream.c:1208:5
    #7 0x1bcfc3c in uv__io_poll /home/kirill/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/linux.c:1565:11
    #8 0x1bca927 in uv_run /home/kirill/.cache/zig/p/N-V-__8AAH34QwB6wi5eQK_lFbfDGSN3hRE8l-6Ep198ZsGg/src/unix/core.c:460:5
    #9 0x1bbe425 in u3_king_commence /home/kirill/work/urbit-repos/vere/pkg/vere/king.c:1061:3
    #10 0x1323f4e in main /home/kirill/work/urbit-repos/vere/pkg/vere/main.c:3320:5
    #11 0x798dcc829d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
```

This PR factors out scry-over-HTTP handling into a separate function
`_http_peek_dispatch` with semitransfer semantics for `req_u->peq_u` and
the contained noun.