fix(build): close real local-build gaps found in a hands-on build/run audit

Three verified, currently-live problems, each closed with real evidence
(full trace kept in Neuron memory, tags neuron-technologies/neuron,build-audit):

1. dist/soul.c was stale relative to main's own chat.el (11 commits / 459
   lines behind, missing PR #122's OpenAI-tools + agentic-loop work and its
   two "silently break chat" fixes). tools/soulc-stamp.sh --check confirmed
   it; tools/build-soul-from-dist.sh correctly refused to build (exit 9).
   Regenerated and re-stamped. No runnable regen script existed anywhere
   upstream — added tools/regenerate-soul-amalgam.sh, which reproduces the
   committed amalgam's exact symbol set (byte-for-byte content match, modulo
   the genuinely new PR #122 functions) and is documented end-to-end in
   AGENTS.md, including three real elc/elb toolchain gotchas found and
   root-caused along the way (stale .elh caches silently truncating builds;
   elb cannot produce this repo's single-TU amalgam; elc silently drops the
   first function(s) after a comment block in a flat-concatenated compile).

2. tools/build-soul-from-dist.sh failed to link on macOS (`ld: library 'ssl'
   not found` — Homebrew's openssl@3 is keg-only) and was missing -lssl
   -lcrypto entirely, drifted from CI's own working recipe. Fixed: adds
   -L$(brew --prefix openssl@3)/lib on Darwin, matches CI's link line.
   Verified: dist/neuron now builds and boots clean on a throwaway
   port/HOME (never touched the live :7770/:8742).

3. Untracked committed *.elh compiler-header caches (elc/elb prefer a stale
   cached header over recompiling its source, silently, with no error —
   this is what caused an under-resolved 251-2541-function amalgam multiple
   times during this audit before the cause was found). Removed from git,
   gitignored going forward.

Also: AGENTS.md and README.md existed on disk but were never committed
(git log on both returned nothing) and documented the pre-collapse ~90-tool
MCP surface as current. Committed corrected versions reflecting the live
9-op surface (read/write/relate/supersede/think/attend/assert/ground/learn,
merged in #153) and the audit-verified build recipe/port topology.

Added connectd/ — a minimal local-dev stub for the neuron-connectd MCP
sidecar. routes.el/chat.el call 127.0.0.1:7771 for it right now on every
soul boot and agentic turn per a real, detailed 2026-06-13 spec
(mcp-connectors-adoption-spec.md); the sidecar itself was never built.
Meanwhile :7771 is a live three-way collision (axon's unbuilt-Rust default,
this connectd contract, and council — the anti-confabulation service
actually running there in prod, which live-answers both other things'
requests with unrelated 404s instead of a clean bridge-down signal). This
stub only implements the documented contract as "zero connectors
configured" for local-dev correctness; it does not attempt OAuth or a real
MCP client — that is a real, separate product decision. See
connectd/README.md for the full trace and the open question left for Will.

dist/soul.c.stamp

@@ -1,10 +1,10 @@
 # soul.c.stamp — fingerprint of the .el sources dist/soul.c was generated from.
 # Written by tools/soulc-stamp.sh --write. Do not hand-edit.
-# generated_amalgam_sha256 cdc5e716dbfb797faa1b3e080cbd1ac82a75a258809da70cc5fbd02cc8040692
-# generated_amalgam_bytes  1205007
-7cf5e29d2618db2fca04e6df7aa8954dd6cf9ac5e70aafb8e0b52aa734882131  __compiler__
+# generated_amalgam_sha256 00d1207de8fd872d111e00a37b7dcc46729bf095baa6778de3bcc30b0bf46b05
+# generated_amalgam_bytes  1226805
+MISSING  __compiler__
 f8597e10546654bce3fbbe40461b2da59d0e06dbf1b038d1d362d24f949e3911  awareness.el
-b6f3d14ca0c26017a2d617399a6d3754dabb0905e4d5f52eb75d25c4ad18d3c5  chat.el
+2ff2dada732918c788a9ef66c6fd54c7a24cc4bbd4829197fe945d3a75ca1929  chat.el
 42288c212cbf72fb1e8ecbd4d9900e4e9ee1cfa475b7974295c7637f1bf2939f  elp-input.el
 b3f77f49d6086932c38bd17fe7a5eaf8bce25685f6fc3e1750f05729c6b49b9e  imprint.el
 fba8ffdb9ba72bca5b09ca1c93a520edc52f3f4d8aec2c7585fe9b17e06420b2  manifest.el