Remove the transfer flag

A transfer was a second verdict carried alongside the tag: a boolean set by
transfer = true in a rule or by x in the TUI, kept in its own pair of rule_
and manual_ columns, whose one real effect was to hold the row out of the
report. The rest of it was display -- a T column in the transaction list, in
the rules screen and in money ls.

Money moved between your own accounts is now tagged like anything else and
counts like anything else. The leg leaving checking is an outflow and the leg
arriving in savings is an inflow, so a report over the whole data root roughly
nets out while one scoped to a single account or month does not. That is the
price of one verdict per transaction instead of two.

A rule now needs a tag, and one that set only transfer = true is refused by
number on load. A leftover transfer key beside a tag is ignored, as unknown
TOML keys always were, and an index built by an older binary drops both
columns when it is opened.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CLAUDE.md

@@ -18,22 +18,22 @@ internal/parser       Parser interface + registry; nlb, revolut, traderepublic
 internal/store        SQLite index (modernc.org/sqlite, no cgo)
 internal/importer     directory walk, dedupe, balance checks
 internal/rules        applies ordered rules to rule_* columns only
-internal/report       per-tag aggregation, transfers excluded
+internal/report       per-tag aggregation
 internal/tui          Bubble Tea models
 ```
 
 ## Invariants
 
-**Rule verdicts and manual edits never share a column.** `rule_tag` /
-`rule_transfer` are rewritten wholesale on every retag; `manual_tag` /
-`manual_transfer` are only ever written by the user. Effective values are
-`COALESCE(manual_*, rule_*)`. This is what makes `money retag` safe to run at
-any time, and it is the first thing to preserve when touching the schema or the
-rules engine. Covered by `TestManualTagSurvivesRetag`.
+**Rule verdicts and manual edits never share a column.** `rule_tag` is
+rewritten wholesale on every retag; `manual_tag` is only ever written by the
+user. The effective tag is `COALESCE(manual_tag, rule_tag)`. This is what makes
+`money retag` safe to run at any time, and it is the first thing to preserve
+when touching the schema or the rules engine. Covered by
+`TestManualTagSurvivesRetag`.
 
 **Statements are the source of truth; the index is disposable.** Deleting
 `index.db` at the root of the data directory and re-importing must reproduce
-everything except manual tags and manual transfer marks.
+everything except the tags set by hand.
 
 **Dedupe is by fingerprint**: `sha256(date | amount | normalised description |
 ordinal)`, where the ordinal distinguishes identical lines *within one
@@ -45,7 +45,7 @@ milliseconds. That is the checksum skip working, not a failure.
 **Money is `int64` minor units**, never a float. Per-account currency, no
 conversion, and totals are never summed across currencies.
 
-**First matching rule wins**, so transfer rules belong above general tag rules.
+**First matching rule wins**, so specific rules belong above general ones.
 A rule setting both `match` and `type` requires both of them.
 `config.AppendRule` therefore appends — never prepends — so saving from the
 rule builder cannot shadow a rule the user wrote by hand.