docs: retire the knowledge-graph plan into the rule graph

[wboayue]

Reviewed plans/ and removed what was no longer a work item.

plans/claude-md-knowledge-graph.md — deleted

It described itself as complete: "Every follow-up is closed; nothing here is a work item." Two parts of it were still referenced, so they move to docs/rules/README.md, which loads on demand rather than every session:

• ## Retired rule numbers — the 27-row rule→node mapping, plus the caveat that numbering shifted mid-use, so an old "rule N" citation resolves against the CLAUDE.md of its own date.
• ## Retrieval check — the three probes, the fail criterion, the 2026-08-06 result, and the warning that the file listing the probes also lists their answers.

The rest — the audit narrative, the prose→gates table, the PR-by-PR log — is history recoverable from git log. Its durable lessons already exist as obligations in CLAUDE.md's Maintaining the rule graph, and the four nodes below absorbed the node-specific reasoning.

References updated: CLAUDE.md now points at docs/rules/README.md#retired-rule-numbers; plans/code-consistency-followups.md cites docs/rules/ directly.

Four nodes absorbed the reasoning worth keeping

• parity/feature-matrix — three green legs don't mean the two sides agree; two sibling tests with the same name and contradictory assertions are a drift report (fix(historical): async retried the wrong case; both sides share the retry helper #744).
• parity/subscription-consumer-idiom — a Client method collecting with while let Some(Ok(..)) turns a routed error into an empty Vec; no shared layer answers this (fix(contracts): propagate routed errors from blocking matching_symbols #735).
• testing/exercise-production-code — read a dead arm before deleting it; a mock hosting a copy of the code under test (refactor(subscriptions): drop dispatcher-intercepted RESPONSE_MESSAGE_IDS entries #734, fix(contracts): propagate routed errors from blocking matching_symbols #735, test(orders): move the submit family off its mock-client shadows #750).
• testing/fixture-builders — a fixture field no assertion reads is unverified input; with_connection_resets (test(stubs): inject Error::ConnectionReset so retry wiring is testable #743, test(wire): one assertion for every rejects-text-framing test #747).

plans/code-consistency-followups.md — pruned, 1,190 → ~580 words

Deleted the closed tracks: the # Examples section (#751, with its count table and per-method list) and the wsh_event_data_* write-up (#752).

Kept and re-verified against main today:

• the two public param-budget deferrals — option_chain and historical_news signatures unchanged;
• the four internal 4+-param sites — all present;
• both market_data realtime-seam items — src/market_data/builder/ still sits a directory above its three siblings, and pub fn market_data in realtime/sync.rs is still pub where realtime_bars / market_depth / tick_by_tick are pub(crate).

Their file.rs:NNN citations became symbol names, per the same decay argument the validator enforces inside nodes.

plans/tick-by-tick-reconnect-decode-desync.md is untouched — open investigation, no fix in the log or CHANGELOG.md.

Checks

Docs-only; no .rs files touched. just rules-check passes — 33 nodes, all links and edges resolve.