refactor: consolidate memory-maintenance-loop wiring into one shared function

[bug-ops]

Summary

• Four near-identical memory-maintenance-loop spawn blocks (src/runner.rs inline, src/serve/deps.rs::spawn_memory_maintenance_loops, src/acp.rs's build_acp_deps, src/daemon.rs's run_daemon) are consolidated into a single shared agent_setup::spawn_memory_maintenance_loops, now called by all four entry points.
• The shared function is parameterized on status_tx: Option<&UnboundedSender<String>> (unifies ACP//sessions* None vs. CLI/TUI/daemon Some for the hebbian-consolidation loop's status sender) and skip_eviction: bool (preserves runner.rs's pre-existing --bare gate, which only ever applied to the eviction loop).
• Closes a test-realism gap: acp.rs/daemon.rs regression tests previously reconstructed a hand-written copy of the spawn block instead of calling production code; both now call the shared function via AppBuilder::for_test.
• Adds 2 targeted unit tests directly on the shared function covering skip_eviction=true and status_tx=Some(...), which were previously untested parameterization (flagged independently by the tester and impl-critic during review).
• No behavior change for any entry point — verified loop-by-loop against the pre-refactor per-file gating by adversarial critique.
• Rebased onto origin/main to reconcile with test: exercise real production wiring in acp/daemon memory-loop tests #6179, which independently extracted acp.rs/daemon.rs's inline blocks into their own per-file wrapper functions after this branch forked; those now-redundant wrappers are removed in favor of the one shared function.

Closes #6180

Test plan

• cargo +nightly fmt --check
• cargo clippy --profile ci --workspace --all-targets --features "desktop,ide,server,chat,pdf,scheduler,testing" -- -D warnings
• cargo nextest run --config-file .github/nextest.toml --workspace --features "desktop,ide,server,chat,pdf,scheduler" --lib --bins (13259 passed, 0 failed)
• RUSTFLAGS="-D warnings" RUSTDOCFLAGS="--deny rustdoc::broken_intra_doc_links" cargo doc --no-deps --workspace --features "desktop,ide,server,chat,pdf,scheduler"
• Targeted re-run of all 6 memory-maintenance-loop tests (4 rewired + 2 new) independently confirmed by reviewer