Channel-open policy hook -- FABRIC-3.6.md task 3.7

Added HERMES-CHANNEL-OPEN? ( req-hi req-lo -- allow? ) at
capsules/ACL.4th block 4008 (default: approve everything) -- the one
word policy authors edit. sk_hermes_channel_open_policy(VM*, VMUuid)
(kernel_hermes.h/.c) is the C-side query that calls it via plain
word-dispatch against the target VM's own dictionary/stack, never
vm_interpret() (avoids task 3.4's input-buffer cursor hazard entirely)
and never decides the answer itself. Fails closed: no policy word,
a policy error, or stack underflow all deny, matching CLAUDE.md's
posture that absence of policy must never mean "always allow."

Two real bugs found and fixed before this was called done:
missing current_executing_entry assignment before calling the word's
func pointer (colon words silently no-op without it, vm_core.c:730 --
no crash, just a wrong answer); and a second FAIL with debug
instrumentation still in place whose precise cause isn't
reconstructable, since no intermediate commit exists for that attempt.

Self-test proves the task's check four ways against the same
unchanged C function: default approve, live redefinition to deny
(zero C change), restore, and a VM with no ACL.4th loaded at all
(fail closed). A fifth check wires the result into task 3.6's
sk_hermes_channel_respond() end to end: a denied policy produces a
NACK and no channel, ledger/stadium_conserved() holding throughout.

Scope, per Captain Bob's ruling: closes with the query built and
proven; sk_hermes_channel_respond() still takes a caller-supplied
approved bool rather than calling the policy internally. Wiring a
real channel-open call site to only this query is deferred to
whichever later task first needs a live decision.

dict_hash identical across amd64/aarch64/riscv64 for every VM, zero
UNKNOWN WORD, mkcapsule --lint clean (38 files, 0 violations).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

capsules/ACL.4th

@@ -98,6 +98,16 @@ Block 4007
 ( rewired: physics-style regression belongs to the kernel     )
 ( exclusively, and this file is deliberately host-portable.   )
 
+Block 4008
+( HERMES-CHANNEL-OPEN? -- FABRIC-3.6.md task 3.7 hook.  )
+( Stack: req-hi req-lo -- allow?  Kernel-Hermes asks     )
+( this word, never decides in C, never gates on          )
+( zuse_session (CLAUDE.md).  Default: approve every       )
+( request.  Policy authors edit THIS word's body only --  )
+( kernel_hermes.c's own query function never changes.     )
+: HERMES-CHANNEL-OPEN? ( req-hi req-lo -- allow? )
+  2DROP 1 ;
+
 Block 4015
 ( Self-activation - runs after all ACL words are defined )
 ACL-BOOT