Retire the old build spec, and point every reference at the architecture (M0.1)

Development Plan M0.1. Every section reference in code, tests, specs/,
the example config, the tuning guide, and the CLAUDE.md and README files
now cites docs/Architecture.md (P, L, D, O, X, Q) instead of the old
spec's A-H, and docs/Architecture-Build-Spec.md is deleted (git keeps
it). The plan's old-to-new table goes with it.

Mostly mechanical, with a per-site choice where one old section split:
A4 became L2 where it meant stop/abandon/the loop and L3 where it meant
approvals; A10 became L6 in the context-budget code and L7 elsewhere; B2
became D4 for outbound Gitea and publishing and D5 for review intake;
'A3 step N' became the matching step of L8's boot sequence. Comments
describing behaviour the architecture drops (planning always escalating,
thresholds tuned at an old build step) now describe the current code and
point at the Development Plan.

docs/Architecture.md gains one line the rewrite missed: intake outages
delay but never fail work (old B2), now in L5, where the poller and
Matrix code cite it.

Comments and docs only; no behaviour change.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

docs/Tuning-Guide.md

@@ -67,7 +67,7 @@ relying on them.)
 Two consequences:
 
 - **Context length is a memory decision, not a free setting.** The spec's
-  estimate (Part H) was about 5 GB left for KV cache beside a 4-bit 32B model.
+  estimate (the original build spec) was about 5 GB left for KV cache beside a 4-bit 32B model.
   At 16-bit, that's only about 20k tokens of context for Qwen3-32B.
 - **KV-cache quantization** stores keys and values in 8 bits (or 4). At 8
   bits it halves the cache and is close to lossless. At 4 bits it is
@@ -170,7 +170,7 @@ How many model calls one milestone may make before the executor stops with
 ### `tuning.executor.failure_limit` — default 2
 
 How many consecutive failed `run_command` calls trigger escalation: the
-sub-task is handed to a frontier model as a delegation (spec A12). A
+sub-task is handed to a frontier model as a delegation (architecture L9). A
 successful command resets the count. Failed file reads don't count, since
 reading is looking around, not doing the work.
 
@@ -192,12 +192,12 @@ reading is looking around, not doing the work.
 
 How many `ask_expert` calls one milestone may make. `ask_expert` is a single
 stateless question to a stronger model, with no access to the repository
-(spec A14), for things like "is this API deprecated?".
+(architecture L9), for things like "is this API deprecated?".
 
 - **Too low:** the executor can't get unstuck on a knowledge question it
   can't answer from the code.
 - **Too high:** a confused executor asks variations of the same question
-  instead of doing the work or failing. That's the circling A12 warns about.
+  instead of doing the work or failing. That's the circling L9 warns about.
 - **Deciding:** count consults per milestone, and check whether the answers
   changed what the executor did next. If it regularly exhausts the budget
   without progress, the budget is fine and the model or the plan is the
@@ -206,7 +206,7 @@ stateless question to a stronger model, with no access to the repository
 ### `tuning.delegation` — hard caps on one delegation
 
 A delegation is a frontier model working a sub-task with full tool access
-(spec A13). When a cap is hit, the delegation **fails**, and its branch and
+(architecture L9). When a cap is hit, the delegation **fails**, and its branch and
 work are discarded, because resuming on a half-edited tree isn't safe.
 
 | Knob | Default | Caps |
@@ -216,7 +216,7 @@ work are discarded, because resuming on a half-edited tree isn't safe.
 | `wall_clock_s` | 900 | elapsed time |
 
 - **`max_tokens` is a scope limit, not the money limit.** Spending limits live
-  on the LiteLLM key (spec A5). This cap stops one delegation from growing
+  on the LiteLLM key (architecture L9). This cap stops one delegation from growing
   without bound. An unbounded one could still exhaust a daily budget and take
   every frontier model away until it resets.
 - **Too low:** delegations fail just short of finishing and their work is
@@ -225,7 +225,7 @@ work are discarded, because resuming on a half-edited tree isn't safe.
 - **Too high:** a stuck delegation burns tokens and time before failing.
 - **Deciding:** every delegation records the tokens it used and how long it
   ran (the `delegation_completed` event, captured for evaluation per spec
-  A16). Set each cap above what successful delegations actually use, with
+  L9). Set each cap above what successful delegations actually use, with
   room to spare.
 
 ### `tuning.tools.command_timeout_s` — default 120