W0110 inline fallback warning + docs refresh

W0110: when a function marked `inline` has a body shape the IR
lowerer can't splice (conditional early return, loops, nested
control flow, empty void body), the analyzer now emits a
warning at the declaration site so the declined hint is
visible instead of silently falling back to a regular JSR.

Implementation:
  - New `W0110` error code in `src/errors/diagnostic.rs` (warning level).
  - New `pub fn can_inline_fun(return_type, body) -> bool` in
    `src/ir/lowering.rs`, extracted from the existing capture
    logic so the analyzer and the IR lowerer share the same
    eligibility rules and can never drift.
  - New `check_inline_declinability` analyzer pass called from
    the tail of `analyze_program`, mirroring the existing
    `check_sprite_scanline_budget` / `check_unreachable_states`
    passes. Emits W0110 with help + note text pointing at the
    two accepted body shapes.
  - `capture_inline_bodies` now defers to `can_inline_fun`
    instead of duplicating the match pattern, so the two sides
    stay in lockstep by construction.

Four regression tests in `src/analyzer/tests.rs` cover the
conditional-return and while-loop declines plus the two
accepted shapes (single-return expression, void sequence).

Example source cleanups: `wrap52` in `examples/war/deck.ne`
and `abs_diff` in both `examples/arrays_and_functions.ne` and
`examples/loop_break_continue.ne` drop the `inline` keyword.
All three were dead hints — the `inline` was being silently
declined before this change, so removing it is source-only;
the three ROMs are byte-identical, all 32 emulator goldens
still match.

Docs refresh
  - `docs/language-guide.md`: rewrote the Inline Functions section
    (real behaviour + W0110), added W0105/W0106/W0107/W0108/W0109/
    W0110 to the warnings table, added the `debug.sprite_overflow*`
    builtins + sprite-per-scanline mitigations section to the
    Debug Mode docs, added a `cycle_sprites` statement entry and
    cross-referenced it from `draw`.
  - `docs/nes-reference.md`: fleshed out the "NEScript Memory
    Usage" block with the full ZP + high-RAM layout, including
    the new `$07EF` / `$07FC` / `$07FD` slots for sprite cycling
    and the debug sprite-overflow telemetry.
  - `docs/future-work.md`: documented all four debug query
    builtins in the "What ships today" block; updated the open
    "OAM allocation strategy" question to reference the shipped
    `cycle_sprites` path and ask about an automatic-flicker
    game attribute as a follow-up.
  - `docs/architecture.md`: updated the `ir/` and `optimizer/`
    module summaries to describe real inline splicing (now
    in lowering, not the optimizer).
  - `README.md`: reframed the `inline` bullet from "hint" to
    "real splicing for single-return / void-body shapes";
    expanded the debug-support bullet to mention the four
    query builtins and their stripping in release builds; added
    a new bullet for the three-layer sprite-per-scanline
    mitigations; bumped the test count from 497 → 694; updated
    the war.ne entry to mention the seven compiler bugs are all
    fixed and point readers at `git log` (instead of the
    deleted COMPILER_BUGS.md).
  - `examples/README.md`: same `git log`-pointing rewrite for
    the war.ne entry.

Deletions
  - `examples/war/COMPILER_BUGS.md` is removed. All seven
    catalogued bugs are fixed; the file's historical value
    lives in `git log` now. Every source-code comment and doc
    reference to the file has been updated to either point at
    `git log` or just describe the bug in place.

Test count: 616 unit + 75 integration + 3 doctests = 694 total.
Clippy / fmt clean. 32/32 emulator goldens match.

https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z

docs/architecture.md

@@ -41,10 +41,10 @@ Each module has a `mod.rs` (implementation) and a co-located `tests.rs` with uni
 `mod.rs`, `tests.rs`. Performs semantic analysis on the AST: type checking, scope and symbol table management, call graph construction with depth analysis, state reachability, unused-variable detection, and dead-code-after-terminator warnings. Emits all user-facing diagnostics beyond lexer/parser syntax errors.
 
 ### `ir/`
-`mod.rs` (types), `lowering.rs` (AST → IR), `tests.rs`. The IR is a flat, register-agnostic representation built from virtual temps and basic blocks. Lowering flattens nested expressions, expands 16-bit operations, desugars `for` into `while`, and resolves constant expressions early.
+`mod.rs` (types), `lowering.rs` (AST → IR), `tests.rs`. The IR is a flat, register-agnostic representation built from virtual temps and basic blocks. Lowering flattens nested expressions, expands 16-bit operations, desugars `for` into `while`, resolves constant expressions early, and performs real `inline fun` splicing — functions marked `inline` whose bodies match one of the two splicable shapes (single `return <expr>` or void statement sequence) are captured before lowering begins and substituted at every call site. Bodies that don't match (conditional returns, loops, nested control flow) fall back to regular out-of-line calls and the analyzer emits `W0110` at the declaration.
 
 ### `optimizer/`
-`mod.rs`, `tests.rs`. Runs passes over the IR in order: strength reduction (mul/div by powers of two, mod by powers of two, ShiftVar → ShiftLeft/Right), function inlining (trivial-function elimination), constant folding (arithmetic + comparisons + shifts), and dead code elimination.
+`mod.rs`, `tests.rs`. Runs passes over the IR in order: strength reduction (mul/div by powers of two, mod by powers of two, ShiftVar → ShiftLeft/Right), constant folding (arithmetic + comparisons + shifts), copy propagation, and dead code elimination. The `inline fun` splicing happens one phase earlier in `ir/lowering.rs` so the optimizer sees already-inlined call sites.
 
 ### `codegen/`
 `ir_codegen.rs`, `peephole.rs`, `mod.rs`. `ir_codegen.rs` walks the optimized IR and emits 6502 instructions; variables land in allocated addresses and IR temps land in a recycling zero-page slot pool. `peephole.rs` runs after codegen to clean up the temp-heavy output (dead-load elimination, branch folding, INC/DEC fold, copy propagation).