docs(citations): replace stale cross-file line-number citations with symbol references

[argszero]

Summary

Comments in three files cited cross-file positions as file.ext:line, and those
line numbers no longer hold the construct the sentence names — a reader
following the pointer lands on unrelated code. This is the line-number sibling
of the §-reference drift fixed in C2022/C2023 (PR #179); line numbers are the
more fragile citation form, because they rot whenever any line is inserted or
deleted above them, regardless of whether the citing sentence is still true.

Measured before the change: 11 such citations in 4 tracked files, of which
6 no longer resolve:

citing site	cited	what it now points at
ui/js/app.js:1021	src/routes/wallet.rs:230-232	if let Some(s) = f
ui/js/app.js:1021	src/routes/wallet.rs:403-405	(blank line)
ui/js/app.js:1021	src/routes/wallet.rs:473	""
src/routes/mod.rs:2390	ops.rs:101	.query_row(
src/routes/mod.rs:2390	ops.rs:175	"uptime_hours": hours,
src/i18n_pack.rs:937	api.js:66	an unrelated comment line (unrecoverable: api.js was rewritten after C2028)

Related Issue

None (no issue exists for this; none was fabricated).

Changes

• ui/js/app.js — the direction-set citation now names the construct
  (TX_INCOME_TYPES / TX_EXPENSE_TYPES, the single source the SQL is
  rendered from) instead of the three dead line numbers.
• src/routes/mod.rs — the ops.rs:101/:175 pair (where total_txs is
  computed and returned) now names ops.rs::runtime.
• src/i18n_pack.rs — the api.js:66 provenance note is unresolvable, so
  the line number is dropped and the provenance sentence kept.
• ui/index.html — app.js cache-bust bumped (20260914-1 → 20260914-2).
• No config / schema / data-structure change (comment-only), so
  config/config.example.toml needs no sync.

Only stale citations are touched: the five that still resolve
(src/routes/ops.rs:94/103, docs/prototype/aitokenpool-console.html:574/1197,
ui/index.html:338) are deliberately left alone — they are the negative control
that proves the change was targeted rather than a blind sweep (same discipline as
C2023, which kept the live db.rs:3 reference). Nothing is renumbered: a new
number would just be another snapshot waiting to rot.

Tests

• cargo test — 217 passed (unchanged; comment-only, no test touched).
• cargo fmt --check — clean.
• cargo clippy --all-targets -- -D warnings — clean.
• Acceptance instrument (a checker over the tracked text, with a
  false-positive control: the smtp.gmail.com:465 host:port must not be
  treated as a citation):
  before population 11 / stale 6 → after population 5 / stale 0,
  and the 5 live citations resolve unchanged.
  The enumeration is shorthand-aware — a naive filename:line regex finds
  only 7 of 11, because the list compresses repeats
  (wallet.rs:230-232 / 403-405 / 473) and drops the filename (:175).

Checklist

• Branch name follows the convention (docs/line-number-citations).
• Commit message uses Conventional Commits (docs(citations): …).
• Single responsibility, minimal change (4 files, +4/−4).